Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed “expected” tax expense	$ 179,113	$ 170,540	$ 270,470
Tax-exempt investment income	(14,666)	(18,833)	(37,209)
Change in valuation allowance	(1,945)	18,576	11,161
Impact of foreign tax rates	7,700	7,683	3,508
State and local taxes	4,842	3,901	1,644
Impact of change in U.S. tax rate	0	(10,950)	(30,531)
Other, net	(6,109)	(7,889)	390
Total expense	$ 168,935	$ 163,028	$ 219,433