Variable Interest Entities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Rabbi Trusts [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net	$ 11,500	$ 10,700
Low Income Housing Tax Credit Partnerships [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net	26,500	18,900
Equity method investments	34,100	29,300
Commitments to fund equity investments	$ 17,400	12,200
Historic Rehabilitation Partnerships [Member]
Variable Interest Entity [Line Items]
Carrying value of VIE assets and liabilities, net		$ 350