Summary of Effective Tax Rate (Details)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Effective income tax rate reconciliation
Federal statutory rate	35.00%	35.00%	35.00%
State taxes, net of federal income tax benefit	4.00%	3.90%	8.10%
Tax-exempt interest income	(12.20%)	(14.00%)	(65.50%)
Tax credits	(3.20%)	(4.20%)	(22.10%)
Goodwill impairment charge	0.00%	0.00%	42.30%
Other, net	0.30%	(0.50%)	0.60%
Effective tax rate	23.90%	20.20%	(1.60%)