Consolidated Statements of Changes in Shareholders’ Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings (Deficit)	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2012	$ 1,415,626	$ 686	$ 1,360,555	$ 180,675	$ (126,290)
Beginning Balance (in shares) at Dec. 31, 2012		68,639,729
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares to stockholders, directors and employees		$ 128	205,130
Issuance of common shares to stockholders, directors and employees (in shares)		12,796,051
Repurchase of common shares from directors and employees	(7,821)	$ (6)	(7,815)
Repurchase of common shares from directors and employees (in shares)		(628,805)
Amortization of share based payments	4,569		4,569
Excess tax benefit from stock based compensation			(333)
Dividends declared	(52,058)			(52,058)
Net income	29,781			29,781
Net change in fair value of derivatives, net of tax expense of $35, $828 and $482, respectively	17,120				17,120
Net derivative loss reclassified into earnings	33,265				33,265
Beginning Balance (in shares) at Dec. 31, 2013		80,806,975
Beginning Balance at Dec. 31, 2013	1,645,407	$ 808	1,562,106	158,398	(75,905)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares to stockholders, directors and employees	0	$ 4	(4)
Issuance of common shares to stockholders, directors and employees (in shares)		354,547
Repurchase of common shares from directors and employees	(2,092)	$ (2)	(2,090)
Repurchase of common shares from directors and employees (in shares)		(178,273)
Amortization of share based payments	4,244		4,244
Excess tax benefit from stock based compensation	924		924
Dividends declared	(66,421)			(66,421)
Net income	100,828			100,828
Net change in fair value of derivatives, net of tax expense of $35, $828 and $482, respectively	2,466				2,466
Net derivative loss reclassified into earnings	$ 34,979				34,979
Beginning Balance (in shares) at Dec. 31, 2014	80,983,249	80,983,249
Beginning Balance at Dec. 31, 2014	$ 1,720,335	$ 810	1,565,180	192,805	(38,460)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common shares to stockholders, directors and employees		$ 3	(3)
Issuance of common shares to stockholders, directors and employees (in shares)		306,593
Repurchase of common shares from directors and employees	(20,881)	$ (11)	(20,870)
Repurchase of common shares from directors and employees (in shares)		(1,057,582)
Amortization of share based payments	5,537		5,537
Excess tax benefit from stock based compensation	493		493
Dividends declared	(72,960)			(72,960)
Net income	121,729			121,729
Net change in fair value of derivatives, net of tax expense of $35, $828 and $482, respectively	1,224				1,224
Net derivative loss reclassified into earnings	$ 24,023				(24,023)
Beginning Balance (in shares) at Dec. 31, 2015	80,232,260	80,232,260
Beginning Balance at Dec. 31, 2015	$ 1,779,500	$ 802	$ 1,550,337	$ 241,574	$ (13,213)