Consolidated Statement of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Loss
Balance at beginning of period at Dec. 31, 2014	$ 1,580,070	$ 129,796	$ 1,665	$ 897,049	$ 1,992,833	$ (1,375,322)	$ (65,951)
Increase (Decrease) in Stockholders' Equity
Net income	50,738				50,738
Other comprehensive income, net of tax	144						144
Dividends on preferred stock	(4,388)				(4,388)
Dividends on common stock	(8,024)				(8,024)
Sales of treasury stock	6,055				(3,765)	9,820
Restricted stock grants				(5,562)	(3,252)	8,814
Forfeitures of restricted stock				583	456	(1,039)
Stock-based compensation	3,916			3,903	13
Net tax benefit excess from stock-based compensation	11			11
Balance at end of period at Jun. 30, 2015	1,628,522	129,796	1,665	895,984	2,024,611	(1,357,727)	(65,807)
Balance at beginning of period at Mar. 31, 2015							(63,460)
Increase (Decrease) in Stockholders' Equity
Net income	31,431
Other comprehensive income, net of tax	(2,347)						(2,347)
Balance at end of period at Jun. 30, 2015	1,628,522	129,796	1,665	895,984	2,024,611	(1,357,727)	(65,807)
Balance at beginning of period at Dec. 31, 2015	1,663,448	129,796	1,665	902,349	2,045,391	(1,357,136)	(58,617)
Increase (Decrease) in Stockholders' Equity
Net income	36,901				36,901
Other comprehensive income, net of tax	5,261						5,261
Dividends on preferred stock	(4,388)				(4,388)
Dividends on common stock	(8,107)				(8,107)
Sales of treasury stock	83				(31)	114
Restricted stock grants				(10,329)	(3,823)	14,152
Forfeitures of restricted stock				950	527	(1,477)
Stock-based compensation	2,107			2,106	1
Net tax benefit excess from stock-based compensation	19			19
Balance at end of period at Jun. 30, 2016	1,695,324	129,796	1,665	895,095	2,066,471	(1,344,347)	(53,356)
Balance at beginning of period at Mar. 31, 2016							(54,207)
Increase (Decrease) in Stockholders' Equity
Net income	18,336
Other comprehensive income, net of tax	851						851
Balance at end of period at Jun. 30, 2016	$ 1,695,324	$ 129,796	$ 1,665	$ 895,095	$ 2,066,471	$ (1,344,347)	$ (53,356)