Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012		Dec. 31, 2011		Mar. 31, 2011
Assets
Cash and due from banks	$ 552,663	[1]	$ 590,801	[2]	$ 406,252	[1]
Overnight investments	752,334	[1]	434,975	[2]	585,286	[1]
Investment securities available for sale	4,457,739	[1]	4,056,423	[2]	4,202,016	[1]
Investment securities held to maturity	1,688	[1]	1,822	[2]	2,341	[1]
Loans held for sale	73,457	[1]	92,539	[2]	48,222	[1]
Loans and leases:
Covered under loss share agreements	2,183,869	[1]	2,362,152	[2]	2,658,134	[1]
Not covered under loss share agreements	11,489,529	[1]	11,581,637	[2]	11,392,351	[1]
Less allowance for loan and lease losses	272,500	[1]	270,144	[2]	232,597	[1]
Net loans and leases	13,400,898	[1]	13,673,645	[2]	13,817,888	[1]
Premises and equipment	864,466	[1]	854,476	[2]	839,463	[1]
Other real estate owned:
Covered under loss share agreements	142,418	[1]	148,599	[2]	137,479	[1]
Not covered under loss share agreements	48,092	[1]	50,399	[2]	49,584	[1]
Income earned not collected	52,406	[1]	42,216	[2]	98,501	[1]
Receivable from FDIC for loss share agreements	410,351	[1]	539,511	[2]	624,322	[1]
Goodwill	102,625	[1]	102,625	[2]	102,625	[1]
Other intangible assets	6,076	[1]	7,032	[2]	9,265	[1]
Other assets	278,415	[1]	286,430	[2]	244,251	[1]
Total assets	21,143,628	[1]	20,881,493	[2]	21,167,495	[1]
Deposits:
Noninterest-bearing	4,572,300	[1]	4,331,706	[2]	4,164,449	[1]
Interest-bearing	13,187,192	[1]	13,245,568	[2]	13,647,287	[1]
Total deposits	17,759,492	[1]	17,577,274	[2]	17,811,736	[1]
Short-term borrowings	677,993	[1]	615,222	[2]	666,417	[1]
Long-term obligations	649,818	[1]	687,599	[2]	801,081	[1]
Other liabilities	164,202	[1]	140,270	[2]	100,047	[1]
Total liabilities	19,251,505	[1]	19,020,365	[2]	19,379,281	[1]
Shareholders' Equity
Surplus	143,766	[1]	143,766	[2]	143,766	[1]
Retained earnings	1,804,498	[1]	1,773,652	[2]	1,673,920	[1]
Accumulated other comprehensive loss	(66,416)	[1]	(66,574)	[2]	(39,907)	[1]
Total shareholders' equity	1,892,123	[1]	1,861,128	[2]	1,788,214	[1]
Total liabilities and shareholders' equity	21,143,628	[1]	20,881,493	[2]	21,167,495	[1]
Class A Common Stock [Member]
Shareholders' Equity
Common stock	8,644	[1]	8,644	[2]	8,757	[1]
Class B Common Stock [Member]
Shareholders' Equity
Common stock	$ 1,631	[1]	$ 1,640	[2]	$ 1,678	[1]

[1] Unaudited

[2] Derived from 2011 Annual Report on Form 10-K.