Commitments and Financial Instruments with Off-Balance-Sheet Risk - Changes in Allowance for Indemnifications Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Change in the allowance for indemnification losses
Provision for indemnifications	$ 36	$ 52
Indemnification reserve for recourse provisions
Change in the allowance for indemnification losses
Allowance, beginning of period	2,303	2,363
Provision for indemnifications	36	52
Allowance, end of period	$ 2,339	$ 2,415