CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive (Loss) Income [Member]	Total
Balance at Dec. 31, 2012	$ 47,556	$ 1,002,603	$ 137,279	$ (43,574)	$ 1,143,864
Net income			87,296		87,296
Other comprehensive (loss) income				10,195	10,195
TOTAL COMPREHENSIVE INCOME					97,491
Tax effect of share-based compensation		(7)			(7)
Share-based compensation expense		6,623			6,623
Issuance of common stock, net	865	(1,301)			(436)
Balance at Dec. 31, 2013	48,421	1,007,918	224,575	(33,379)	1,247,535
Net income			107,936		107,936
Other comprehensive (loss) income				(8,239)	(8,239)
TOTAL COMPREHENSIVE INCOME					99,697
Tax effect of share-based compensation		786			786
Share-based compensation expense		18,616			18,616
Issuance of common stock, net	250	(1,379)			(1,129)
Balance at Dec. 31, 2014	48,671	1,025,941	332,511	(41,618)	1,365,505
Net income			45,292		45,292
Other comprehensive (loss) income				(547)	(547)
TOTAL COMPREHENSIVE INCOME					44,745
Tax effect of share-based compensation		(186)			(186)
Share-based compensation expense		9,477			9,477
Issuance of common stock, net	402	284			686
Balance at Dec. 31, 2015	$ 49,073	$ 1,035,516	$ 377,803	$ (42,165)	$ 1,420,227