Consolidated Statements Of Stockholders' Equity Consolidated Statements Of Stockholders' Equity - USD ($) $ in Thousands	Total	Series A Preferred Stock [Member]	Series B Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] Series A Preferred Stock [Member]	Additional Paid-in Capital [Member] Series B Preferred Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance, shares at Dec. 31, 2013		5,064	4,155	46,105,076
Beginning balance at Dec. 31, 2013	$ 706,418	$ 0	$ 0	$ 461	$ 216,872	$ 4,774	$ 6,575	$ 484,850	$ 4,235
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	125,327							125,327
Other comprehensive income, net of tax	(11,362)								(11,362)
Dividends	$ (52,269)							(52,269)
Exercise of stock options, shares	433,008			433,008
Exercise of stock options	$ 6,621			$ 4	6,617
Issuance of shares under Employee Stock Purchase Plan, shares				5,735
Issuance of shares under Employee Stock Purchase Plan	265			$ 0	265
Equity portion of convertible debt	36,478				36,478
Vested restricted stock, shares				565,713
Vested restricted stock				$ 6	(6)
Repurchase and retirement of common stock, shares				(113,256)
Repurchase and retirement of common stock	(5,663)			$ (1)	(2,245)			(3,417)
Extinguishment of Series A preferred stock, shares		5,064		235,665
Extinguishment of Series A preferred stock				$ 2	989	(4,774)		(991)
Exchange of Series B preferred stock, shares			4,155	177,573
Exchange of Series B preferred stock				$ (2)	(2)		6,575
Share based compensation	8,908				8,824			84
Excess tax benefit on share based compensation	5,512				5,512
Ending balance at Dec. 31, 2014	820,235	$ 0	$ 0	$ 474	273,304	0	0	553,584	(7,127)
Ending balance, shares at Dec. 31, 2014		0	0	47,409,514
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	133,636							133,636
Other comprehensive income, net of tax	(21,997)								(21,997)
Dividends	$ (58,826)							(58,826)
Exercise of stock options, shares	221,221			221,221
Exercise of stock options	$ 4,958			$ 2	4,956
Issuance of shares under Employee Stock Purchase Plan, shares				4,020
Issuance of shares under Employee Stock Purchase Plan	260				260
Vested restricted stock, shares				278,092
Vested restricted stock				$ 3	(3)
Repurchase and retirement of common stock, shares				(53,904)
Repurchase and retirement of common stock	(3,674)			$ (1)	(1,955)			(1,718)
Exchange of Series B preferred stock, shares				91,734
Exchange of Series B preferred stock				$ 1	(1)
Share based compensation	11,130				11,017			113
Excess tax benefit on share based compensation	4,486				4,486
Ending balance at Dec. 31, 2015	890,208	$ 0	$ 0	$ 479	292,064	0	0	626,789	(29,124)
Ending balance, shares at Dec. 31, 2015		0	0	47,950,677
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	152,439							152,439
Other comprehensive income, net of tax	(25,525)								(25,525)
Dividends	$ (65,835)							(65,835)
Exercise of stock options, shares	142,870			142,870
Exercise of stock options	$ 3,570			$ 1	3,569
Issuance of shares under Employee Stock Purchase Plan, shares				3,918
Issuance of shares under Employee Stock Purchase Plan	254			$ 0	254
Vested restricted stock, shares				270,098
Vested restricted stock				$ 3	(3)
Repurchase and retirement of common stock, shares				(1,015,584)
Repurchase and retirement of common stock	(56,496)			$ (10)	(3,344)			(53,142)
Exchange of Series B preferred stock, shares				91,737
Exchange of Series B preferred stock				$ 1	(1)
Share based compensation	13,650				13,519			131
Excess tax benefit on share based compensation	2,271				$ 2,271
Ending balance at Dec. 31, 2016	$ 914,536	$ 0	$ 0	$ 474		$ 0	$ 0	$ 660,382	$ (54,649)
Ending balance, shares at Dec. 31, 2016		0	0	47,443,716	308,329,000