Commitments and Contingencies (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Commitment to Extend Credits and Unused Lines of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 1,400.0	$ 1,300.0
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Obligation instrument term	5 years
Commitments - maximum potential obligation	$ 42.4	31.5
Commercial Letters of Credit [Member]
Guarantor Obligations [Line Items]
Commitments - maximum potential obligation	$ 0.0	$ 11.3