Consolidated Statements Of Shareholders' Equity - 3 months ended Mar. 31, 2017 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balances, shares at Dec. 31, 2016	49,330	49,330
Balances, value at Dec. 31, 2016	$ 1,365,465	$ 4,933	$ 626,306	$ 748,402	$ (14,176)
Stock-based compensation expense	$ 2,160	$ 0	2,160	0	0
Shares repurchased and retired, shares	(31)	(31)
Shares repurchased and retired, value	$ (1,000)	$ (3)	(345)	(652)	0
Stock options exercised, shares	256	256
Stock options exercised, value	$ 5,141	$ 26	5,115	0	0
Vesting of restricted stock units, shares	166	166
Vesting of restricted stock units, value	$ 0	$ 16	(16)	0	0
Shares withheld for taxes, shares	(11)	(11)
Shares withheld for taxes, value	$ (358)	$ (1)	(357)	0	0
Net income	9,687	0	0	9,687	0
Other comprehensive loss	$ 964	$ 0	0	0	964
Balances, shares at Mar. 31, 2017	49,710	49,710
Balances, value at Mar. 31, 2017	$ 1,382,059	$ 4,971	$ 632,863	$ 757,437	$ (13,212)