Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details) (USD $)	12 Months Ended
	Dec. 31, 2011 state	Dec. 31, 2010	Dec. 31, 2009
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 12,309,385,000	$ 11,386,628,000
Less: Allowance for loan and lease losses	(262,557,000)	(257,007,000)	(288,493,000)
Loans and leases, excluding covered loans, net	12,046,828,000	11,129,621,000
Covered loans	1,481,854,000	1,857,522,000
Less: Allowance for loan losses	(64,565,000)	(67,389,000)
Covered loans, net	1,417,289,000	1,790,133,000
Total loans and leases	13,791,239,000	13,244,150,000
Net loans and leases	13,464,117,000	12,919,754,000
Unamortized fees, net of deferred costs	7,500,000	6,500,000
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	58,700,000	54,800,000
New loans and advances made	50,700,000
Repayments of loans and advances	45,300,000
Interest income recognized	2,600,000	2,100,000	2,300,000
LTV ratio on residential mortgage loans (as a percent)	90.00%
Interest-only residential mortgages	1,050,000,000	975,400,000
Interest-only home equity lines of credit	741,100,000	733,700,000
Number of states with largest concentration within covered loan portfolio	5
Company pledged loans as collateral	5,690,000,000
California
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	83.00%
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	8.00%
New York
Accounts notes and loans receivable
Percent of total loans excluding covered loans outstanding	7.00%
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	7.00%
Percent of total covered loans	33.00%
Commercial
Accounts notes and loans receivable
Loans and leases, excluding covered loans	4,846,594,000	4,136,874,000
Covered loans	30,911,000	55,082,000
Commercial real estate mortgages
Accounts notes and loans receivable
Loans and leases, excluding covered loans	2,110,749,000	1,958,317,000
Less: Allowance for loan and lease losses	(45,967,000)	(52,516,000)	(52,011,000)
Covered loans	1,288,352,000	1,569,739,000
Residential mortgage
Accounts notes and loans receivable
Loans and leases, excluding covered loans	3,763,218,000	3,552,312,000
Less: Allowance for loan and lease losses	(14,029,000)	(16,753,000)	(12,797,000)
Covered loans	14,931,000	18,380,000
Real estate construction
Accounts notes and loans receivable
Loans and leases, excluding covered loans	315,609,000	467,785,000
Less: Allowance for loan and lease losses	(23,347,000)	(40,824,000)	(53,722,000)
Covered loans	140,992,000	204,945,000
Equity lines of credit
Accounts notes and loans receivable
Loans and leases, excluding covered loans	741,081,000	733,741,000
Less: Allowance for loan and lease losses	(8,024,000)	(7,229,000)	(3,734,000)
Covered loans	5,167,000	6,919,000
Installment loan
Accounts notes and loans receivable
Loans and leases, excluding covered loans	132,647,000	160,144,000
Less: Allowance for loan and lease losses	(1,959,000)	(3,931,000)	(4,665,000)
Covered loans	1,501,000	2,457,000
Lease financing
Accounts notes and loans receivable
Loans and leases, excluding covered loans	$ 399,487,000	$ 377,455,000