Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	$ 1,855,900	$ 1,719,709	$ 1,429,517
Other comprehensive income (loss) before reclassifications	(4,108)	3,029
Amounts reclassified from accumulated other comprehensive income (loss)	(589)	(1,736)
Total other comprehensive income (loss)	(4,697)	1,293	16,257
Balance at end of period	1,990,239	1,855,900	1,719,709
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	23,812	22,519	6,262
Total other comprehensive income (loss)	(4,697)	1,293	16,257
Balance at end of period	19,115	23,812	22,519
Defined Benefit Pension
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	2,659	6,303
Other comprehensive income (loss) before reclassifications	(6,890)	(1,908)
Amounts reclassified from accumulated other comprehensive income (loss)	(589)	(1,736)
Total other comprehensive income (loss)	(7,479)	(3,644)
Balance at end of period	(4,820)	2,659	6,303
Foreign Currency Translation
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Balance at beginning of period	21,153	16,216
Other comprehensive income (loss) before reclassifications	2,782	4,937
Amounts reclassified from accumulated other comprehensive income (loss)	0	0
Total other comprehensive income (loss)	2,782	4,937
Balance at end of period	$ 23,935	$ 21,153	$ 16,216