Derivative Instruments (Gross Notional Amount and Fair Value of Derivatives Contracts) (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Derivative [Line Items]
Assets	$ 42,714	$ 34,413
Liabilities	(8,457)	(13,043)
Derivative, Notional Amount	615,816	577,719
Derivatives Designated as Hedge Accounting Instruments:
Derivative [Line Items]
Assets	14,212	4,653
Liabilities	0	(1,504)
Derivative, Notional Amount	133,255	131,212
Derivatives Designated as Hedge Accounting Instruments: | Foreign Currency Swaps
Derivative [Line Items]
Assets	14,212	4,653
Liabilities	0	(1,504)
Derivative, Notional Amount	133,255	131,212
Derivatives Not Qualifying as Hedge Accounting Instruments:
Derivative [Line Items]
Assets	28,502	29,760
Liabilities	(8,457)	(11,539)
Derivative, Notional Amount	482,561	446,507
Derivatives Not Qualifying as Hedge Accounting Instruments: | Interest Rate Swaps
Derivative [Line Items]
Assets	5,177	3,005
Liabilities	0	(5)
Derivative, Notional Amount	30,200	32,075
Derivatives Not Qualifying as Hedge Accounting Instruments: | Credit Default Swaps
Derivative [Line Items]
Assets	9	0
Liabilities	0	0
Derivative, Notional Amount	713	0
Derivatives Not Qualifying as Hedge Accounting Instruments: | Foreign Currency Swaps
Derivative [Line Items]
Assets	5,447	2,691
Liabilities	0	(579)
Derivative, Notional Amount	33,224	33,224
Derivatives Not Qualifying as Hedge Accounting Instruments: | Foreign Currency Forward
Derivative [Line Items]
Assets	1	0
Liabilities	(66)	(36)
Derivative, Notional Amount	2,249	1,858
Derivatives Not Qualifying as Hedge Accounting Instruments: | Equity Options
Derivative [Line Items]
Assets	17,868	24,064
Liabilities	(8,391)	(10,919)
Derivative, Notional Amount	$ 416,175	$ 379,350