CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Dec. 31, 2010	$ 126,386	$ 470	$ 14,087	$ 114,990	$ (3,161)
Increase (Decrease) in Stockholders' Equity
Net income	58,011			58,011
Other comprehensive loss	(11,342)				(11,342)
Shares issued for consideration:
Exercise of stock options	13,151	15	13,136
Income tax effect from the exercise of stock options and vesting of restricted stock	1,668		1,668
Shares issued under stock incentive plan
Shares issued under employee stock purchase plan	37		37
Shares issued to Board of Directors in lieu of cash	50		50
Stock-based compensation	9,671		9,671
Cash dividend	(17,183)			(17,183)
Purchase of common stock	(15,026)	(8)	(15,018)
Balance at Dec. 31, 2011	165,423	477	23,631	155,818	(14,503)
Increase (Decrease) in Stockholders' Equity
Net income	50,001			50,001
Other comprehensive loss	(10,377)				(10,377)
Shares issued for consideration:
Exercise of stock options	1,041	2	1,039
Income tax effect from the exercise of stock options and vesting of restricted stock	(2,652)		(2,652)
Shares issued under stock incentive plan	3	3
Shares issued to Board of Directors in lieu of cash	50		50
Stock-based compensation	10,356		10,356
Cash dividend	(21,069)			(21,069)
Purchase of common stock	(4,676)	(3)	(4,673)
Balance at Dec. 31, 2012	188,100	479	27,751	184,750	(24,880)
Increase (Decrease) in Stockholders' Equity
Net income	23,146			23,146
Other comprehensive loss	30,782				30,782
Shares issued for consideration:
Exercise of stock options	3,979	3	3,976
Income tax effect from the exercise of stock options and vesting of restricted stock	643		643
Shares issued under stock incentive plan	4	4
Shares issued to Board of Directors in lieu of cash	50		50
Stock-based compensation	10,473		10,473
Cash dividend	(23,097)			(23,097)
Purchase of common stock	(5,638)	(3)	(5,635)
Balance at Dec. 31, 2013	$ 228,442	$ 483	$ 37,258	$ 184,799	$ 5,902