Income Taxes (Schedule of Effective Income Tax Rate Reconciliation) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense (Benefit), Continuing Operations, Income Tax Reconciliation [Abstract]
Computed “expected” tax expense	$ 148,008	$ 179,113	$ 170,540
Tax-exempt investment income	(12,770)	(14,666)	(18,833)
Change in valuation allowance	46,238	(1,945)	18,576
Impact of foreign tax rates	6,753	7,700	7,683
State and local taxes	2,561	4,842	3,901
Impact of change in U.S. tax rate	0	0	(10,950)
Other, net	(18,973)	(6,109)	(7,889)
Total expense	$ 171,817	$ 168,935	$ 163,028