Derivatives and Hedging Activity - Designated and Non-Designated Hedges (Details) - 12 months ended Dec. 31, 2016 $ in Thousands, € in Millions	EUR (€) instrument item	USD ($) instrument item
Derivatives
Number of contracts	262	262
Foreign exchange contracts | DKK | Sell
Derivatives
Number of contracts	1	1
Aggregate notional amount | $		$ 5,960
Foreign exchange contracts | EUR | Sell
Derivatives
Number of contracts	59	59
Aggregate notional amount | $		$ 297,128
Foreign exchange contracts | EUR | Sell | Ireland Portfolio
Derivatives
Number of contracts	42	42
Aggregate notional amount | €	€ 239.3
Foreign exchange contracts | GBP | Sell
Derivatives
Number of contracts	163	163
Aggregate notional amount | $		$ 266,402
Foreign exchange contracts | NOK | Sell
Derivatives
Number of contracts	1	1
Aggregate notional amount | $		$ 836
Foreign exchange contracts | SEK | Sell
Derivatives
Number of contracts	1	1
Aggregate notional amount | $		$ 1,317
Interest rate swaps | USD | Paying fixed rates
Derivatives
Number of contracts	24	24
Aggregate notional amount | $		$ 705,955
Interest rate swaps | USD | Receiving fixed rates
Derivatives
Number of contracts	1	1
Aggregate notional amount | $		$ 8,000
Interest rate swaps | Derivatives designated as hedging instruments
Derivatives
Number of contracts | instrument	6	6
Aggregate notional amount | $		$ 55,600
Fixed monthly coupons at fixed rate, low end of range (as a percent)	0.60%	0.60%
Fixed monthly coupons at fixed rate, high end of range (as a percent)	1.52%	1.52%
Hedging period for covering exposure to the variability in future cash flows	53 months
Interest rate caps | EUR
Derivatives
Number of contracts	2	2
Aggregate notional amount | $		$ 294,000
Interest rate caps | USD
Derivatives
Number of contracts	6	6
Aggregate notional amount | $		$ 52,210
Credit index instruments | USD
Derivatives
Number of contracts	4	4
Aggregate notional amount | $		$ 14,000