Other Comprehensive Income (Summary Of Tax Expense (Benefit) Of Other Comprehensive Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Other Comprehensive Income (Loss), Tax [Abstract]
Net holding gains arising during the period	$ 93,935	$ 71,381	$ 168,928	$ 187,880
Change in unrealized other-than-temporary impairment losses on fixed maturities arising during the period	0	9	0	(6)
Reclassification adjustments for net gains (losses) included in net income	136	(2,333)	(2,396)	(7,810)
Change in net unrealized gains on investments	94,071	69,057	166,532	180,064
Change in foreign currency translation adjustments	(466)	(1,618)	(503)	(1,695)
Change in net actuarial pension loss	154	86	333	188
Total	$ 93,759	$ 67,525	$ 166,362	$ 178,557