Consolidated Statements Of Changes In Shareholders' Equity - USD ($) $ in Thousands	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 for the period	220,760			220,760
Other comprehensive income, net of tax	55,264				55,264
Subordinated debt converted to preferred stock	31	$ 36	$ (5)
Net activity under employee plans and related tax benefits, shares			435,269
Net activity under employee plans and related tax benefits	13,117		$ 13,117
Dividends on preferred stock	(40,080)			(40,080)
Dividends on common stock	(14,873)			(14,873)
Change in deferred compensation	1,308			1,308
Balance at Jun. 30, 2014	6,700,090	$ 1,004,006	$ 4,192,136	1,640,785	(136,837)
Balance (in shares) at Jun. 30, 2014			185,112,965
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 for the period	$ 105,985			105,985
Other comprehensive income, net of tax	92,869				92,869
Subordinated debt converted to preferred stock	15	21	$ (6)
Net activity under employee plans and related tax benefits, shares			726,011
Net activity under employee plans and related tax benefits	14,423		$ 14,423
Dividends on preferred stock	(31,806)			(31,806)
Dividends on common stock	(20,444)			(20,444)
Change in deferred compensation	(397)			(397)
Balance at Jun. 30, 2015	$ 7,530,175	$ 1,004,032	$ 4,738,272	$ 1,823,043	$ (35,172)
Balance (in shares) at Jun. 30, 2015	203,192,991		203,740,914