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	142,077							142,077
Other comprehensive income, net of income taxes	16,431						16,431
Cash dividends declared on common stock	(29,194)							(29,194)
Cash dividends paid on Series C Preferred Stock	(7,678)				(7,678)
Issuance of stock, net of issuance costs	118		118
Restricted share unit activity	(468)			41	(509)
Stock options exercised	1,985			116	1,869
Share-based compensation net tax (deficiency) benefit	(3,164)				(3,164)
Share-based compensation expense	7,453				7,453
Balance at Sep. 30, 2014	3,076,545		125,980	139,878	2,974,319	(114,176)	(24,827)	(24,629)
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	167,684							167,684
Other comprehensive income, net of income taxes	6,513						6,513
Cash dividends declared on common stock	(39,736)							(39,736)
Cash dividends paid on Series C Preferred Stock		$ (7,678)							$ (7,678)
Issuance of stock, net of issuance costs	(162,138)				14,516	(176,654)
Restricted share unit activity	(4,461)			282	(4,376)			(367)
Stock options exercised	4,897			294	4,603
Share-based compensation net tax (deficiency) benefit	1,303				1,303
Share-based compensation expense	9,462				9,462
Balance at Sep. 30, 2015	$ 3,017,116		$ 125,980	$ 140,526	$ 2,986,333	$ (364,428)	$ (6,092)	$ 134,797