Consolidated Statements of Changes in Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Preferred Stock [Member]
Balance, value at Dec. 31, 2013	$ 1,053,249	$ 860,562	$ 202,514	$ (12,044)	$ 2,217
Balance, shares at Dec. 31, 2013		51,265,000			8,782
Net income	62,654		62,654
Other comprehensive income	11,549			11,549
Issuance of common stock - cashless exercise of warrants, shares		1,140,000
Issuance of common stock - cashless exercise of warrants, value	0	$ 0
Stock Adjustment Value Deferred Compensation	(1)	$ (1)
Stock Adjustment Deferred Compensation - Shares		0
Issuance of common stock - stock option and other plans, value	915	$ 915
Issuance of common stock - stock option and other plans, shares		40,000
Issuance of common stock - restricted stock awards, net of cancelled awards, value	2,041	$ 2,041
Issuance of common stock - restricted stock awards, net of cancelled awards, shares		228,000
Stock Repurchased and Retired During Period, Value	(605)	$ (605)
Stock Repurchased During Period, Shares		(24,000)
Dividends, Preferred Stock, Cash	(66)		(66)
Cash dividends paid on common stock	(33,525)		(33,525)
Balance, value at Sep. 30, 2014	1,096,211	$ 862,912	231,577	(495)	$ 2,217
Balance, shares at Sep. 30, 2014		52,649,000			8,782
Balance, value at Dec. 31, 2014	1,228,175	$ 985,839	234,498	5,621	$ 2,217
Balance, shares at Dec. 31, 2014		57,437,000			8,782
Net income	72,087		72,087
Other comprehensive income	7,205			7,205
Issuance of common stock - stock option and other plans, value	1,194	$ 1,194
Issuance of common stock - stock option and other plans, shares		46,000
Issuance of common stock - restricted stock awards, net of cancelled awards, value	2,934	$ 2,934
Issuance of common stock - restricted stock awards, net of cancelled awards, shares		277,000
Stock Repurchased and Retired During Period, Value	(879)	$ (879)
Stock Repurchased During Period, Shares		(31,000)
Dividends, Preferred Stock, Cash	(100)		(100)
Cash dividends paid on common stock	(56,480)		(56,480)
Balance, value at Sep. 30, 2015	$ 1,254,136	$ 989,088	$ 250,005	$ 12,826	$ 2,217
Balance, shares at Sep. 30, 2015		57,729,000			8,782