Consolidated Statements Of Changes In Shareholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Preferred Stock [Member]	Common Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Dec. 31, 2013	$ 6,464,563	$ 1,003,970	$ 4,179,024	$ 1,473,670	$ (192,101)
Balance (in shares) at Dec. 31, 2013			184,677,696
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	101,210			101,210
Other comprehensive income, net of tax	46,639				46,639
Net activity under employee plans and related tax benefits, shares			217,486
Net activity under employee plans and related tax benefits	6,489		6,489
Dividends on preferred stock	(25,020)			(25,020)
Dividends on common stock	(7,436)			(7,436)
Change in deferred compensation	(229)			(229)
Balance at Mar. 31, 2014	6,586,216	1,003,970	4,185,513	1,542,195	(145,462)
Balance (in shares) at Mar. 31, 2014			184,895,182
Balance at Dec. 31, 2014	7,369,530	1,004,011	4,723,855	1,769,705	(128,041)
Balance (in shares) at Dec. 31, 2014	203,014,903		203,014,903
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) for the period	92,025			92,025
Other comprehensive income, net of tax	13,132				13,132
Subordinated debt converted to preferred stock	15	21	(6)
Net activity under employee plans and related tax benefits, shares			178,088
Net activity under employee plans and related tax benefits	4,707		4,707
Dividends on preferred stock	(16,746)			(16,746)
Dividends on common stock	(8,176)			(8,176)
Change in deferred compensation	(189)			(189)
Balance at Mar. 31, 2015	$ 7,454,298	$ 1,004,032	$ 4,728,556	$ 1,836,619	$ (114,909)
Balance (in shares) at Mar. 31, 2015	203,192,991		203,192,991