STOCK-BASED COMPENSATION PLANS - (Details)						1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
STOCK-BASED COMPENSATION PLANS - (Details)	Apr. 01, 2017 shares	Mar. 31, 2017 executive shares	Mar. 16, 2017 shares	Apr. 01, 2016 executive shares	Mar. 16, 2015 executive shares	Feb. 28, 2017 executive shares	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) $ / shares shares	Sep. 30, 2016 USD ($)	Dec. 31, 2015 executive	Jun. 09, 2017 shares	Dec. 31, 2016 shares
Stock-based compensation
Stock authorized for issuance (in shares)							120,000,000		120,000,000				120,000,000
Common stock, capital shares held, conversion ratio												1.50
Range of assumptions used in estimating fair value of options
Expected life							5 years		5 years
Cash received from the exercise of stock options (in dollars) \| $									$ 149,000	$ 135,000
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							$ 3,887,000	$ 6,408,000	11,387,000	15,464,000
Tax benefit from stock based compensation expense \| $									0	0
Fair value of the assumed awards attributable to future stock-based compensation expense \| $							15,400,000		$ 15,400,000
Expected period for unrecognized expense									2 years
Product cost of revenue [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							75,000	95,000	$ 261,000	259,000
Service cost of revenue [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							199,000	331,000	777,000	985,000
Research and development [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							1,095,000	1,298,000	3,650,000	3,687,000
Sales and marketing [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							871,000	3,048,000	1,690,000	5,292,000
General and Administrative Expense [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $							$ 1,647,000	$ 1,636,000	$ 5,009,000	$ 5,241,000
Performance Share Units [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)									147,085
Granted (in shares)									165,000
Vested (in shares)									(47,856)
Forfeited (in shares)									(10,060)
Unvested balance at the end of the period (in shares)							254,169		254,169
Weighted average grant-date fair value
Unvested balance at the end of the period (in dollars per share) \| $ / shares									$ 12.11
Granted (in dollars per share) \| $ / shares									8.41
Vested (in dollars per share) \| $ / shares									13.04
Forfeited (in dollars per share) \| $ / shares									11.87
Unvested balance at end of the period (in dollars per share) \| $ / shares							$ 9.54		$ 9.54
Total fair value (in dollars) \| $									$ 600,000
Stock Options [Member]
Number of shares
Outstanding at the beginning of the period (in shares)									5,610,106
Granted (in shares)									6,480
Exercised (in shares)									(31,643)
Forfeited (in shares)									(35,107)
Expired (in shares)									(397,690)
Outstanding at the end of the period (in shares)							5,152,146		5,152,146
Vested or expected to vest at the end of the period (in shares)							5,130,390		5,130,390
Exercisable at the end of the period (in shares)							4,824,340		4,824,340
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share) \| $ / shares									$ 15.73
Granted (in dollars per share) \| $ / shares									6.53
Exercised (in dollars per share) \| $ / shares									4.70
Forfeited (in dollars per share) \| $ / shares									13.79
Expired (in dollars per share) \| $ / shares									23.57
Outstanding at the end of the period (in dollars per share) \| $ / shares							$ 15.19		15.19
Vested or expected to vest at the end of the period (in dollars per share) \| $ / shares							15.21		15.21
Exercisable at the end of the period (in dollars per share) \| $ / shares							$ 15.25		$ 15.25
Weighted average remaining contractual life (in years)
Outstanding at the end of the period									4 years 9 months 23 days
Vested or expected to vest at the end of the period									4 years 9 months 13 days
Exercisable at the end of the period									4 years 7 months 18 days
Aggregate intrinsic value (in dollars)
Outstanding at the end of the period (in dollars) \| $							$ 177,000		$ 177,000
Vested or expected to vest at the end of the period (in dollars) \| $							172,000		172,000
Exercisable at the end of the period (in dollars) \| $							$ 141,000		$ 141,000
Range of assumptions used in estimating fair value of options
Risk-free interest rate									1.95%
Expected dividends							0.00%		0.00%
Weighted average volatility							50.70%		51.20%
Expected life									5 years
Weighted average grant date fair value of stock options granted (in dollars per share) \| $ / shares							$ 3.11		$ 3.00
Total intrinsic values of stock options exercised (in dollars) \| $							$ 17,000		$ 80,000
Cash received from the exercise of stock options (in dollars) \| $							$ 59,000		$ 149,000
Restricted stock awards [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)									2,030,028
Granted (in shares)									735,912
Vested (in shares)									(820,632)
Forfeited (in shares)									(25,426)
Unvested balance at the end of the period (in shares)							1,919,882		1,919,882
Weighted average grant-date fair value
Unvested balance at the end of the period (in dollars per share) \| $ / shares									$ 9.69
Granted (in dollars per share) \| $ / shares									6.86
Vested (in dollars per share) \| $ / shares									10.37
Forfeited (in dollars per share) \| $ / shares									13.02
Unvested balance at end of the period (in dollars per share) \| $ / shares							$ 8.28		$ 8.28
Total fair value (in dollars) \| $									$ 8,800,000
Restricted Stock Units (RSUs) [Member]
Change in unvested restricted stock awards
Unvested balance at the beginning of the period (in shares)									110,219
Granted (in shares)									0
Vested (in shares)									(36,694)
Forfeited (in shares)									(11,628)
Unvested balance at the end of the period (in shares)							61,897		61,897
Weighted average grant-date fair value
Unvested balance at the end of the period (in dollars per share) \| $ / shares									$ 11.95
Granted (in dollars per share) \| $ / shares									0.00
Vested (in dollars per share) \| $ / shares									7.04
Forfeited (in dollars per share) \| $ / shares									8.71
Unvested balance at end of the period (in dollars per share) \| $ / shares							$ 7.05		$ 7.05
Employee Stock [Member]
Weighted average grant-date fair value
Offering period									6 months
Purchase price of common stock (percentage)									85.00%
Maximum number of shares purchasable per employee									500
2017 Performance Share Units [Member] \| Performance Share Units [Member]
Stock-based compensation
Number of executives granted shares \| executive		5
Change in unvested restricted stock awards
Granted (in shares)		165,000
2017 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche One [Member]
Stock-based compensation
Vesting percentage		33.33%
2017 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Two [Member]
Stock-based compensation
Vesting percentage		33.33%
2017 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Three [Member]
Stock-based compensation
Vesting percentage		33.33%
2016 Performance Share Units [Member] \| Performance Share Units [Member]
Stock-based compensation
Number of executives granted shares \| executive				6		4
Percent of performance metrics achieved						90.40%
Change in unvested restricted stock awards
Granted (in shares)				131,250
Vested (in shares)						(24,106)
Forfeited (in shares)			(2,560)
2016 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche One [Member]
Stock-based compensation
Vesting percentage				33.33%
2016 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Two [Member]
Stock-based compensation
Vesting percentage				33.33%
2016 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Three [Member]
Stock-based compensation
Vesting percentage				33.33%
2015 Performance Share Units [Member] \| Performance Share Units [Member]
Stock-based compensation
Number of executives granted shares \| executive					8	4					2
Percent of performance metrics achieved						76.00%
Change in unvested restricted stock awards
Granted (in shares)					131,250
Vested (in shares)						(23,750)
Forfeited (in shares)	(7,500)
2015 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche One [Member]
Stock-based compensation
Vesting percentage					33.33%
2015 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Two [Member]
Stock-based compensation
Vesting percentage					33.33%
2015 Performance Share Units [Member] \| Performance Share Units [Member] \| Share-based Compensation Award, Tranche Three [Member]
Stock-based compensation
Vesting percentage					33.33%
Restatement Adjustment [Member] \| Sales and marketing [Member]
Weighted average grant-date fair value
Stock-based compensation (in dollars) \| $									$ (1,000,000)
Common Stock [Member]
Stock-based compensation
Stock authorized for issuance (in shares)												900,000

SONUS NETWORKS INC 10-Q