Borrowings - Schedule of Retirement of Exchangeable Senior Notes (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Debt Instrument [Line Items]
Reacquisition price			$ 247,454	$ 0
Net loss on extinguishment of debt	$ 1,344	$ 0	6,581	$ 0
Exchangeable Senior Notes
Debt Instrument [Line Items]
Reacquisition price	62,068		247,454
Par value of Notes retired during the period	(60,933)		(242,178)
Write off of unamortized debt issuance cost associated with Notes retired during the period	209		1,305
Net loss on extinguishment of debt	$ 1,344		$ 6,581