Income Taxes (Reconciliation To Effective Rate) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%		35.00%
Expected federal income tax expense (benefit)	$ (268,890)	$ 387,286	$ 391,158
Non-taxable investment income	(12,019)	(18,954)	(46,625)
Tax credits	(11,708)	(13,694)	(10,358)
Changes in tax law	0	(193,306)	882,175
Other	1,516	172	(15,251)
Total income tax expense (benefit)	$ (291,101)	$ 161,504	$ 1,201,099
Effective tax rate	22.70%	8.80%	107.50%