Commitments and Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Loss Contingencies [Line Items]
Number of months in which the majority of loan commitments are expected to fund loans	3 months
Loss Contingency, Estimate of Possible Loss	$ 0
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
Operating leases, future minimum payments due - 2015	14,800,000
Operating leases, future minimum payments due - 2016	12,200,000
Operating leases, future minimum payments due - 2017	6,400,000
Operating leases, future minimum payments due - 2018	3,900,000
Operating leases, future minimum payments due - 2019	2,400,000
Operating leases, future minimum payments due - 2020 and thereafter	$ 9,200,000
Consumer Price Index increase	3.00%
Operating lease rent expense	$ 15,600,000	$ 12,400,000	$ 11,600,000
Commitments to Extend Credit [Member]
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	$ 1,590,000,000	1,080,000,000
Expiration period of commitments to extend credit	1 year
Face amount of off-balance sheet liability with expiration greater than five years	$ 144,000,000
Commitments to Extend Credit [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Expiration period of commitments to extend credit	5 years
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	$ 39,000,000	41,000,000
Loan Origination Commitments [Member]
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	294,000,000	251,000,000
Loan Origination Commitments [Member] | Real Estate Residential Loans [Member]
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	$ 23,000,000	$ 24,000,000