Commitments, Contingencies and Guarantees - Warranties (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
Changes in the activity related to liability recorded in connection with representations and warranties
Reserve balance at beginning of period	$ 5,469	$ 3,825	$ 6,459	$ 4,048
Addition of fair value of representations and warranties due to acquisitions	0	3,100	0	3,100
Reserve reduction	(71)	0	(1,061)	(150)
Charge-offs	(9)	0	(9)	(73)
Ending reserve balance	5,389	6,925	5,389	6,925
Reserve balance
Liability for specific claims					$ 506	$ 730
General allowance					4,883	5,729
Total reserve balance	$ 5,469	$ 3,825	$ 6,459	$ 4,048	$ 5,389	$ 6,459