Commitments and Contingencies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Loss Contingencies [Line Items]
Undisbursed loan commitments	$ 578,200	$ 293,600
Consumer Price Index increase	2.10%
Allowance for credit losses on lending-related commitments	$ 1,300	0
Commitments to Extend Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	2,700,000	1,590,000
Standby Letters of Credit
Loss Contingencies [Line Items]
Face amount of off-balance sheet liability	118,900	38,800
Performance guarantee
Loss Contingencies [Line Items]
Outstanding balance of loans	16,900	1,500
Maximum potential amount of undiscounted future payments	16,100	1,500
Recourse liability	$ 200	$ 100