Borrowings - Schedule of Contractual Maturities of Reverse Repurchase Agreements (Details) - Securities sold under agreements to repurchase - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
2018	$ 200,000
2019	600,000
2020	300,000
Total	$ 1,100,000	$ 1,100,000	$ 1,100,000