Income Taxes (Details 3)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Effective income tax rate reconciliation
Statutory rate (as a percent)	35.00%	35.00%	35.00%
Net state income tax (as a percent)	6.10%	6.20%	5.90%
Tax exempt income (as a percent)	(4.20%)	(4.00%)	(6.30%)
Affordable housing investments (as a percent)	(4.70%)	(5.00%)	(7.20%)
FTB settlement and other adjustments (as a percent)			(9.50%)
All other, net (as a percent)	(0.10%)	(1.60%)	(1.70%)
Effective tax provision (benefit) (as a percent)	32.10%	30.60%	16.20%