Pensions - Schedule of Benefit Obligations and Plan Assets Rollforward (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Nov. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Change in Benefit Obligations
Balance as of January 1		$ 643,961	$ 597,077
Interest cost		13,949	22,146	$ 20,946
Actuarial loss, net		63,164	76,161
Benefits paid		(66,746)	(51,423)
Annuity purchase		(17,831)	0
Balance as of December 31		636,497	643,961	597,077
Change in Plan Assets
Balance as of January 1		449,019	424,927
Plan contributions		44,908	30,369
Actual return on plan assets, net of administrative expenses		34,878	45,146
Benefits paid		(66,746)	(51,423)
Annuity purchase	$ (17,800)	(17,831)	0
Balance as of December 31		444,228	449,019	$ 424,927
Funded Status as of December 31 (plan assets less benefit obligations)		$ (192,269)	$ (194,942)