Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details) (USD $)	Mar. 31, 2012 state	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 12,747,902,000	$ 12,309,385,000	$ 11,269,684,000
Less: Allowance for loan and lease losses	(266,077,000)	(262,557,000)	(263,356,000)	(257,007,000)
Loans and leases, excluding covered loans, net	12,481,825,000	12,046,828,000
Covered loans	1,397,156,000	1,481,854,000
Less: Allowance for loan losses	(61,471,000)	(64,565,000)	(82,016,000)	(67,389,000)
Covered loans, net	1,335,685,000	1,417,289,000
Total loans and leases	14,145,058,000	13,791,239,000
Net loans and leases	13,817,510,000	13,464,117,000
Unamortized fees, net of deferred costs	8,200,000	7,500,000
Number of states with largest concentration within covered loan portfolio	5
California
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	82.00%
Percent of total covered loans	39.00%
Nevada
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	3.00%
Percent of total covered loans	7.00%
New York
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	6.00%
Percent of total covered loans	5.00%
Texas
Accounts notes and loans receivable
Percent of total covered loans	11.00%
Arizona
Accounts notes and loans receivable
Percent of total covered loans	4.00%
Other states
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	9.00%
Percent of total covered loans	34.00%
Commercial
Accounts notes and loans receivable
Loans and leases, excluding covered loans	5,175,396,000	4,846,594,000
Covered loans	22,395,000	30,911,000
Commercial real estate mortgages
Accounts notes and loans receivable
Loans and leases, excluding covered loans	2,213,114,000	2,110,749,000	1,902,862,000
Less: Allowance for loan and lease losses	(46,586,000)	(45,967,000)	(47,519,000)	(52,516,000)
Covered loans	1,219,923,000	1,288,352,000
Residential mortgage
Accounts notes and loans receivable
Loans and leases, excluding covered loans	3,805,807,000	3,763,218,000	3,603,058,000
Less: Allowance for loan and lease losses	(13,803,000)	(14,029,000)	(13,527,000)	(16,753,000)
Covered loans	13,378,000	14,931,000
Real estate construction
Accounts notes and loans receivable
Loans and leases, excluding covered loans	313,409,000	315,609,000	415,241,000
Less: Allowance for loan and lease losses	(22,096,000)	(23,347,000)	(36,693,000)	(40,824,000)
Covered loans	135,065,000	140,992,000
Equity lines of credit
Accounts notes and loans receivable
Loans and leases, excluding covered loans	715,997,000	741,081,000	733,567,000
Less: Allowance for loan and lease losses	(8,032,000)	(8,024,000)	(6,445,000)	(7,229,000)
Covered loans	5,210,000	5,167,000
Installment loan
Accounts notes and loans receivable
Loans and leases, excluding covered loans	125,793,000	132,647,000	146,779,000
Less: Allowance for loan and lease losses	(1,938,000)	(1,959,000)	(5,445,000)	(3,931,000)
Covered loans	1,185,000	1,501,000
Lease financing
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 398,386,000	$ 399,487,000