Accumulated Other Comprehensive Income (Loss) (Components of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Before-Tax
Net change	$ (19,908)	$ 7,254
Tax Effect
Net change	7,894	(2,626)
Net-of-Tax
Net unrealized (losses) gains arising during the period	(10,513)	6,062
Net realized gains reclassified into net income	(1,501)	(1,434)
Other comprehensive (loss) income	(12,014)	4,628
Available- for-Sale Investment Securities
Before-Tax
Net unrealized (losses) gains arising during the period	(24,577)	8,721
Net realized gains reclassified into net income	(2,129)	(2,474)
Net change	(26,706)	6,247
Tax Effect
Net unrealized (losses) gains arising during the period	7,266	(3,666)
Net realized gains reclassified into net income	628	1,040
Net change	7,894	(2,626)
Net-of-Tax
Net unrealized (losses) gains arising during the period	(17,311)	5,055
Net realized gains reclassified into net income	(1,501)	(1,434)
Other comprehensive (loss) income	(18,812)	3,621
Foreign Currency Translation Adjustments
Before-Tax
Net unrealized (losses) gains arising during the period	6,798	1,007
Net change	6,798	1,007
Tax Effect
Net unrealized (losses) gains arising during the period	0	0
Net change	0	0
Net-of-Tax
Net unrealized (losses) gains arising during the period	6,798	1,007
Net realized gains reclassified into net income	0	0
Other comprehensive (loss) income	$ 6,798	$ 1,007