Accumulated Other Comprehensive Loss (After-tax Components of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2020		Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		$ 1,195,655		$ 876,764
Other comprehensive loss before reclassifications		(20,974)		(2,770)
Amounts reclassified from accumulated other comprehensive income (loss)		556		11,631
Net current-period other comprehensive income (loss)		(20,418)		8,861
Ending Balance		1,113,862		998,286
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(7,231)		(6,387)
Ending Balance		(27,649)		2,474
Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		(9,443)		(126)
Other comprehensive loss before reclassifications		(14,390)		(3,758)
Amounts reclassified from accumulated other comprehensive income (loss)		727		136
Net current-period other comprehensive income (loss)		(13,663)		(3,622)
Ending Balance		(23,106)		(3,748)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		1,065		(11,550)
Other comprehensive loss before reclassifications		(6,639)		943
Amounts reclassified from accumulated other comprehensive income (loss)		0		11,666
Net current-period other comprehensive income (loss)		(6,639)		12,609
Ending Balance		(5,574)		1,059
Investment in Convertible Preferred Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		258		258
Other comprehensive loss before reclassifications	[1]	0		0
Amounts reclassified from accumulated other comprehensive income (loss)		0	[1]	0
Net current-period other comprehensive income (loss)		0		0
Ending Balance		258		258
Defined Benefit Plan Items
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning Balance		889		5,031
Other comprehensive loss before reclassifications		55		45
Amounts reclassified from accumulated other comprehensive income (loss)		(171)		(171)
Net current-period other comprehensive income (loss)		(116)		(126)
Ending Balance		$ 773		$ 4,905

[1] All amounts are net of tax. Amounts in parentheses indicate debits