CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balances at beginning of period at Dec. 31, 2016	$ (269,911)	$ 423	$ 1,043,063	$ (1,271,148)	$ (32,353)	$ (9,896)
Balances at beginning of period (in shares) at Dec. 31, 2016		42,339			(1,612)
Stock issued pursuant to employee stock plans	(884)	$ 0	(15,565)	0	$ 14,681	0
Stock issued pursuant to employee stock plans (in shares)					629
Stock-based compensation	8,311	0	8,311	0	$ 0	0
Repurchase of common stock	0
Net (loss) income	(13,555)	0	0	(13,555)	0	0
Other comprehensive income (loss)	7,470	0	0	0	0	7,470
Partial retirement of convertible senior notes conversion feature	(5)		(5)
Partial unwind capped call cash receipt	4		4
Balances at end of period at Dec. 31, 2017	(268,570)	$ 423	1,035,808	(1,284,703)	$ (17,672)	(2,426)
Balances at end of period (in shares) at Dec. 31, 2017		42,339			(983)
Cumulative-effect adjustment due to adoption of ASU No. 2016-09	108,367			108,367
Stock issued pursuant to employee stock plans	(643)		(13,084)		$ 12,441
Stock issued pursuant to employee stock plans (in shares)					592
Stock-based compensation	6,258		6,258
Repurchase of common stock	0
Net (loss) income	(10,674)			(10,674)
Other comprehensive income (loss)	(1,341)					(1,341)
Partial retirement of convertible senior notes conversion feature	(74)		(74)
Partial unwind capped call cash receipt	16		16
Balances at end of period at Dec. 31, 2018	$ (166,661)	$ 423	1,028,924	(1,187,010)	$ (5,231)	(3,767)
Balances at end of period (in shares) at Dec. 31, 2018	41,948	42,339			(391)
Stock issued pursuant to employee stock plans	$ (3,270)	$ 7	(8,508)		$ 5,231
Stock issued pursuant to employee stock plans (in shares)	811				391
Stock-based compensation	$ 7,958		7,958
Repurchase of common stock	(76,269)
Net (loss) income	7,601			7,601
Other comprehensive income (loss)	(163)					(163)
Partial retirement of convertible senior notes conversion feature	(577)		(577)
Partial unwind capped call cash receipt	27		27
Balances at end of period at Dec. 31, 2019	$ (155,085)	$ 430	$ 1,027,824	$ (1,179,409)	$ 0	$ (3,930)
Balances at end of period (in shares) at Dec. 31, 2019	43,150	43,150			0