Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 14,818,295,000	$ 12,309,385,000
Less: Allowance for loan and lease losses	(277,888,000)	(262,557,000)	(257,007,000)
Loans and leases, excluding covered loans, net	14,540,407,000	12,046,828,000
Covered loans	1,031,004,000	1,481,854,000
Less: Allowance for loan losses	(44,781,000)	(64,565,000)	(67,389,000)
Covered loans, net	986,223,000	1,417,289,000
Total loans and leases	15,849,299,000	13,791,239,000
Net loans and leases	15,526,630,000	13,464,117,000
Unamortized fees, net of deferred costs	5,900,000	7,500,000
Aggregate amount of loans to executive officers, directors and companies and individuals affiliated with or guaranteed by officers and directors of the Company and the Bank	87,900,000	58,700,000
New loans and advances made	104,300,000
Repayments of loans and advances	74,100,000
Interest income recognized	2,200,000	2,600,000	2,100,000
Number of states with largest concentration within covered loan portfolio	5
Company pledged loans as collateral	6,270,000,000
California
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	80.00%
Percent of total covered loans	38.00%
Nevada
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	2.00%
Percent of total covered loans	8.00%
New York
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	7.00%
Percent of total covered loans	4.00%
Texas
Accounts notes and loans receivable
Percent of total covered loans	12.00%
Ohio
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	11.00%
Percent of total covered loans	34.00%
Commercial
Accounts notes and loans receivable
Loans and leases, excluding covered loans	6,211,353,000	4,846,594,000
Covered loans	10,561,000	30,911,000
Commercial real estate mortgages
Accounts notes and loans receivable
Loans and leases, excluding covered loans	2,829,694,000	2,110,749,000
Less: Allowance for loan and lease losses	(48,240,000)	(45,967,000)	(52,516,000)
Covered loans	931,758,000	1,288,352,000
Residential mortgage
Accounts notes and loans receivable
Loans and leases, excluding covered loans	3,962,205,000	3,763,218,000
Less: Allowance for loan and lease losses	(10,499,000)	(14,029,000)	(16,753,000)
Covered loans	5,652,000	14,931,000
Real estate construction
Accounts notes and loans receivable
Loans and leases, excluding covered loans	222,780,000	315,609,000
Less: Allowance for loan and lease losses	(13,130,000)	(23,347,000)	(40,824,000)
Covered loans	78,554,000	140,992,000
Equity lines of credit
Accounts notes and loans receivable
Loans and leases, excluding covered loans	711,750,000	741,081,000
Less: Allowance for loan and lease losses	(7,243,000)	(8,024,000)	(7,229,000)
Covered loans	3,790,000	5,167,000
Installment loan
Accounts notes and loans receivable
Loans and leases, excluding covered loans	142,793,000	132,647,000
Less: Allowance for loan and lease losses	(1,847,000)	(1,959,000)	(3,931,000)
Covered loans	689,000	1,501,000
Lease financing
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 737,720,000	$ 399,487,000