Other Comprehensive Income (Loss) (Summary Of Tax Expense (Benefit) Of Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Other Comprehensive Income (Loss), Tax [Abstract]
Net holding gains (losses) arising during the period	$ 40,818	$ (28,230)
Reclassification adjustments for net gains (losses) included in net income (loss)	(66)	217
Change in net unrealized gains (losses) on available-for-sale investments	40,752	(28,013)
Change in foreign currency translation adjustments	0	766
Change in net actuarial pension loss	362	136
Total	$ 41,114	$ (27,111)

Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss).

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