Commitments and Contingencies - Summary of Allowance for Loan Repurchases or Indemnifications (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Commitments And Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 2,842	$ 2,546	$ 2,659	$ 2,156
Provision for loan repurchases or indemnifications	201	313	384	703
Losses on loans repurchased or indemnified	(6)		(6)
Balance at end of period	$ 3,037	$ 2,859	$ 3,037	$ 2,859