Fair Value Measurement - Summary of Financial Assets Measured at Fair Value on Recurring Basis Using Significant Unobservable Inputs (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2017 USD ($)
Investment Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance, beginning of period	$ 1,080
Amortization	2
Change in unrealized loss	(5)
Balance, end of period	1,077
Servicing Assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Balance, beginning of period	21,091
Additions, net	2,948
Change in fair value	(2,615)
Balance, end of period	$ 21,424