Consolidated Statement of Changes in Stockholders' Equity - 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, 2013	$ 1,519,513	$ 129,796	$ 1,665	$ 894,297	$ 1,930,026	$ (1,398,021)	$ (38,250)
Increase (Decrease) in Stockholders' Equity
Net income	72,657				72,657
Other comprehensive income, net of tax	7,716						7,716
Dividends on preferred stock ($48.75 per share)	(6,582)				(6,582)
Dividends on common stock ($0.12 per share)	(11,929)				(11,929)
Sales of treasury stock (479,751 shares)	6,092				(3,410)	9,502
Restricted stock grants (429,752 shares)				(5,422)	(3,450)	8,872
Forfeitures of restricted stock (63,716 shares)				281	206	(487)
Stock-based compensation	6,488			6,477	11
Net tax benefit excess from stock-based compensation	51			51
Balance at end of period at Sep. 30, 2014	1,594,006	129,796	1,665	895,684	1,977,529	(1,380,134)	(30,534)
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	69,644				69,644
Other comprehensive income, net of tax	3,518						3,518
Dividends on preferred stock ($48.75 per share)	(6,582)				(6,582)
Dividends on common stock ($0.12 per share)	(12,052)				(12,052)
Sales of treasury stock (479,751 shares)	6,124				(3,789)	9,913
Restricted stock grants (429,752 shares)				(5,608)	(3,273)	8,881
Forfeitures of restricted stock (63,716 shares)				747	569	(1,316)
Stock-based compensation	6,432			6,415	17
Net tax benefit excess from stock-based compensation	28			28
Balance at end of period at Sep. 30, 2015	$ 1,647,182	$ 129,796	$ 1,665	$ 898,631	$ 2,037,367	$ (1,357,844)	$ (62,433)