Pension Plans and Postretirement Benefits - Components of Defined Benefit Pension Plans (Details) - U.S. - USD ($) $ in Thousands	11 Months Ended	12 Months Ended
	Nov. 30, 2018	Dec. 31, 2017	Dec. 31, 2016
Change in Benefit Obligation [Roll Forward]
Projected benefit obligation at beginning of year	$ 211,257	$ 205,405
Interest cost	6,783	8,119	$ 8,464
Actuarial (gains) losses	(16,646)	6,644
Settlement payments	(3,133)	0
Benefits paid	(7,000)	(8,911)
Projected benefit obligation at end of year	191,261	211,257	205,405
Change in Fair Value of Plan Assets [Roll Forward]
Fair value of plan assets at beginning of year	150,806	127,514
Actual return on plan assets	(7,676)	22,192
Employer contributions	8,890	12,417
Benefits paid	(7,000)	(8,911)
Settlement payments	(3,133)	0
Administrative expenses	(2,895)	(2,406)
Fair value of plan assets at end of year	138,992	150,806	$ 127,514
Funded status at end of year	$ (52,269)	$ (60,451)