Income Tax (Provision for Income Tax Expense) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current Income Tax Expense (Benefit), Continuing Operations [Abstract]
Current Federal Tax Expense (Benefit)	$ 78,431	$ 131,108	$ 1,020
Current Federal Tax Expense (Benefit) Relating To US Tax Reform	(68,080)	0	0
Current Foreign Tax Expense (Benefit)	43,120	36,830	47,706
Current Income Tax Expense (Benefit)	53,471	167,938	48,726
Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract]
Deferred Federal Income Tax Expense (Benefit)	62,890	159,853	273,928
Deferred Federal Income Tax Expense (Benefit) Related To US Tax Reform	5,907	(1,033,755)	0
Tax Adjustments, Settlements, and Unusual Provisions	(62,173)	(1,033,755)	0
Deferred Foreign Income Tax Expense (Benefit)	7,710	26,598	19,849
Deferred income taxes	76,507	(847,304)	293,777
Income Tax Expense (Benefit)	$ 129,978	$ (679,366)	$ 342,503