Revenue and Accounts Receivable - Contract Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Contract with Customer, Asset, Net, Current [Roll Forward]
Contract with Customer, Receivable, Net, Current	$ 296,355	$ 309,075
Contract with Customer, Receivable, Current, Net Increase (Decrease)	13,853	7,803
Contract with Customer, Receivable, Net, Current	310,208	316,878
Contract with Customer, Asset, Gross, Current	31,525	2,833
Contract with Customer, Contract Asset, Current, Net Increase (Decrease)	(24,756)	72,701
Contract with Customer, Asset, Gross, Current	6,769	75,534
Contract with Customer, Asset, Net, Noncurrent [Roll Forward]
Contract with Customer, Receivable, Net, Noncurrent	63,554	60,948
Contract with Customer, Receivable, NonCurrent, Net Increase (Decrease)	(1,613)	1,700
Contract with Customer, Receivable, Net, Noncurrent	61,941	62,648
Contract with Customer, Asset, Gross, Noncurrent	2,504	541
Increase (Decrease) in Contract Receivables, Net	3,376	6,740
Contract with Customer, Asset, Gross, Noncurrent	5,880	7,281
Contract with Customer, Liability, Current [Roll Forward]
Contract with Customer, Liability, Current	2,492	4,016
Contract with Customer, Liability, Current, Net Increase (Decrease)	9,553	1,049
Contract with Customer, Liability, Current	12,045	5,065
Contract with Customer, Liability, Noncurrent [Roll Forward]
Contract with Customer, Liability, Noncurrent	615	1,731
Contract with Customer, Liability, Noncurrent, Net Increase (Decrease)	(234)	(812)
Contract with Customer, Liability, Noncurrent	$ 381	$ 919