Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2012	19,559			612
Balance at Dec. 31, 2012	$ 20,000	$ 237,262,000	$ 206,577,000	$ (13,868,000)	$ (1,241,000)	$ 428,750,000
Net income			39,330,000			39,330,000
Other comprehensive income					251,000	251,000
Equity compensation		8,786,000				8,891,000
Exercise of stock options (in shares)	159
Exercise of stock options		$ 3,102,000				$ 3,103,000
Issuance of shares pursuant to vesting of restricted stock units (in shares)	294
Net payments for stock issuances and buybacks (in shares)	(247)	1,213		246		1,213
Net payments for stock issuances and buybacks		$ 335,000		$ (7,782,000)		$ (7,447,000)
Balance (in shares) at Dec. 31, 2013	19,765			853
Balance at Dec. 31, 2013	$ 21,000	250,698,000	245,907,000	$ (21,545,000)	(990,000)	474,091,000
Net income			40,030,000			40,030,000
Other comprehensive income					(1,491,000)	(1,491,000)
Equity compensation		10,680,000		$ 328,000		11,008,000
Exercise of stock options (in shares)	85
Exercise of stock options		1,831,000				1,831,000
Issuance of shares pursuant to vesting of restricted stock units (in shares)	333
Net payments for stock issuances and buybacks (in shares)	(753)			753
Net payments for stock issuances and buybacks		454,000		$ (28,777,000)		(28,323,000)
Balance (in shares) at Dec. 31, 2014	19,430			1,606
Balance at Dec. 31, 2014	$ 21,000	267,206,000	285,937,000	$ (49,994,000)	(2,481,000)	500,689,000
Tax impact of stock option exercises and award vesting		3,543,000				3,543,000
Net income			39,369,000			39,369,000
Other comprehensive income					(5,010,000)	(5,010,000)
Equity compensation		10,392,000		$ 458,000		10,850,000
Exercise of stock options (in shares)	44
Exercise of stock options		932,000				932,000
Issuance of shares pursuant to vesting of restricted stock units (in shares)	234
Net payments for stock issuances and buybacks (in shares)	(676)			676
Net payments for stock issuances and buybacks		276,000		$ (25,137,000)		(24,861,000)
Balance (in shares) at Dec. 31, 2015	19,032			2,282
Balance at Dec. 31, 2015	$ 21,000	280,113,000	$ 325,306,000	$ (74,673,000)	$ (7,491,000)	523,276,000
Tax impact of stock option exercises and award vesting		$ 1,307,000				$ 1,307,000