Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Series C Preferred Stock [Member]	Preferred Stock [Member] Series C Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings (Deficit) [Member]	Retained Earnings (Deficit) [Member] Series C Preferred Stock [Member]
Balance at Dec. 31, 2013	$ 2,948,985		$ 125,862	$ 139,721	$ 2,976,348	$ (114,176)	$ (41,258)	$ (137,512)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	95,289							95,289
Other comprehensive income, net of income taxes	27,542						27,542
Cash dividends declared on common stock	(19,460)							(19,460)
Cash dividends paid on Series C Preferred Stock	(5,119)				(5,119)
Issuance of stock, net of issuance costs	118		118
Restricted share unit activity	(468)			39	(507)
Stock options exercised	1,304			75	1,229
Share-based compensation net tax benefit	162
Share-based compensation expense	4,698				4,698
Balance at Jun. 30, 2014	3,053,051		125,980	139,835	2,976,811	(114,176)	(13,716)	(61,683)
Balance at Dec. 31, 2014	3,041,270		125,980	139,950	2,960,825	(187,774)	(12,605)	14,894
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	109,756							109,756
Other comprehensive income, net of income taxes	(9,718)						(9,718)
Cash dividends declared on common stock	(26,664)							(26,664)
Cash dividends paid on Series C Preferred Stock		$ (5,119)							$ (5,119)
Issuance of stock, net of issuance costs	(109,570)				14,515	(124,085)
Restricted share unit activity	(4,403)			278	(4,314)			(367)
Stock options exercised	3,271			197	3,074
Share-based compensation net tax benefit	1,063				1,063
Share-based compensation expense	6,271				6,271
Balance at Jun. 30, 2015	$ 3,006,157		$ 125,980	$ 140,425	$ 2,981,434	$ (311,859)	$ (22,323)	$ 92,500