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, 2013	$ (359,335)	$ 423	$ 1,043,384	$ (1,336,526)	$ (72,543)	$ 5,927
Balances at beginning of period (in shares) at Dec. 31, 2013		42,339			(3,257)
Stock issued pursuant to employee stock plans	(436)		(4,928)		$ 4,492
Stock issued pursuant to employee stock plans (in shares)					212
Stock-based compensation	11,513		11,513
Purchase of capped call transactions	0
Repurchase of common stock	0
Net income	14,728			14,728
Other comprehensive loss	(7,540)					(7,540)
Balances at end of period at Dec. 31, 2014	(341,070)	$ 423	1,049,969	(1,321,798)	$ (68,051)	(1,613)
Balances at end of period (in shares) at Dec. 31, 2014		42,339			(3,045)
Stock issued pursuant to employee stock plans	3,476		(14,215)		$ 17,691
Stock issued pursuant to employee stock plans (in shares)					823
Stock-based compensation	9,514		9,514
Convertible notes conversion feature (net of taxes of $6,493 and net of issuance cost of $1,088)	20,718		20,718
Purchase of capped call transactions	(10,125)		(10,125)
Repurchase of common stock	(7,999)		(23)		$ (7,976)
Repurchase of common stock (in shares)					(587)
Net income	2,480			2,480
Other comprehensive loss	(6,566)					(6,566)
Balances at end of period at Dec. 31, 2015	$ (329,572)	$ 423	1,055,838	(1,319,318)	$ (58,336)	(8,179)
Balances at end of period (in shares) at Dec. 31, 2015	39,530	42,339			(2,809)
Cumulative-effect adjustment due to adoption of ASU No. 2016-09	$ 0		49	(49)
Stock issued pursuant to employee stock plans	5,243		(20,740)		$ 25,983
Stock issued pursuant to employee stock plans (in shares)					1,197
Stock-based compensation	7,916		7,916
Purchase of capped call transactions	0
Repurchase of common stock	0
Net income	48,219			48,219
Other comprehensive loss	(1,717)					(1,717)
Balances at end of period at Dec. 31, 2016	$ (269,911)	$ 423	$ 1,043,063	$ (1,271,148)	$ (32,353)	$ (9,896)
Balances at end of period (in shares) at Dec. 31, 2016	40,727	42,339			(1,612)