Variable Interest Entities (Details) (USD $)	Dec. 31, 2012
Rabbi Trusts [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net	$ 10,000,000
Low Income Housing Tax Credit Partnerships [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net	10,600,000
Equity method investments	28,800,000
Historic Rehabilitation Partnerships [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net	350,000
Equity method investments	$ 8,000,000