Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Dec. 31, 2012		Jun. 30, 2012
Assets
Cash and due from banks	$ 542,645	[1]	$ 639,730	[2]	$ 571,004	[1]
Overnight investments	1,039,925	[1]	443,180	[2]	984,536	[1]
Investment securities available for sale	5,184,976	[1]	5,226,228	[2]	4,634,248	[1]
Investment securities held to maturity	1,130	[1]	1,342	[2]	1,578	[1]
Loans held for sale	62,497	[1]	86,333	[2]	76,374	[1]
Loans and leases:
Acquired	1,443,336	[1]	1,809,235	[2]	1,999,351	[1]
Originated	11,655,469	[2]	11,576,115	[2]	11,462,458	[2]
Less allowance for loan and lease losses	258,316	[1]	319,018	[2]	272,929	[1]
Net loans and leases	12,840,489	[1]	13,066,332	[2]	13,188,880	[1]
Premises and equipment	872,477	[1]	882,768	[2]	873,483	[1]
Other real estate owned:
Covered under loss share agreements in other real estate owned	84,833	[1]	102,577	[2]	117,381	[1]
Not covered under loss share agreements in other real estate owned	36,942	[1]	43,513	[2]	49,454	[1]
Income earned not collected	45,567	[1]	47,666	[2]	49,743	[1]
Receivable from FDIC for loss share agreements	158,013	[1]	270,192	[2]	405,626	[1]
Goodwill	102,625	[1]	102,625	[2]	102,625	[1]
Other intangible assets	2,266	[1]	3,556	[2]	5,175	[1]
Other assets	334,437	[1]	367,610	[2]	272,531	[1]
Total assets	21,308,822	[1]	21,283,652	[2]	21,332,638	[1]
Liabilities
Noninterest-bearing	5,151,378	[1]	4,885,700	[2]	4,761,369	[1]
Interest-bearing	12,866,637	[1]	13,200,325	[2]	13,040,277	[1]
Total deposits	18,018,015	[1]	18,086,025	[2]	17,801,646	[1]
Short-term borrowings	581,937	[1]	568,505	[2]	700,299	[1]
Long-term obligations	443,313	[1]	444,921	[2]	644,682	[1]
Payable to FDIC for loss share agreements	101,652		101,641		91,648
Other liabilities	224,575	[1]	218,553	[2]	164,573	[1]
Total liabilities	19,369,492	[1]	19,419,645	[2]	19,402,848	[1]
Shareholders' Equity
Surplus	143,766	[1]	143,766	[2]	143,766	[1]
Retained earnings	1,886,121	[1]	1,792,726	[2]	1,838,160	[1]
Accumulated other comprehensive loss	(100,176)	[1]	(82,106)	[2]	(62,407)	[1]
Total shareholders' equity	1,939,330	[1]	1,864,007	[2]	1,929,790	[1]
Total liabilities and shareholders' equity	21,308,822	[1]	21,283,652	[2]	21,332,638	[1]
Class A Common Stock
Shareholders' Equity
Common stock	8,586	[1]	8,588	[2]	8,644	[1]
Class B Common Stock
Shareholders' Equity
Common stock	$ 1,033	[1]	$ 1,033	[2]	$ 1,627	[1]

[1] Unaudited

[2] Derived from 2012 Annual Report on Form 10-K.