Revenue - Contract Balances (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)
Contract with Customer, Asset, Net, Current [Abstract]
Contract with Customer, Receivable, Net, Current	$ 184,993
Contract with Customer, Receivable, Current, Net Increase (Decrease)	124,082
Contract with Customer, Receivable, Net, Current	309,075
Contract with Customer, Asset, Gross, Current	0
Contract with Customer, Contract Asset, Current, Net Increase (Decrease)	2,833
Contract with Customer, Asset, Gross, Current	2,833
Contract with Customer, Asset, Net, Noncurrent [Abstract]
Contract with Customer, Receivable, Net, Noncurrent	34,008
Contract with Customer, Receivable, NonCurrent, Net Increase (Decrease)	26,940
Contract with Customer, Receivable, Net, Noncurrent	60,948
Contract with Customer, Asset, Gross, Noncurrent	0
Increase (Decrease) in Contract Receivables, Net	541
Contract with Customer, Asset, Gross, Noncurrent	541
Contract with Customer, Liability, Current [Abstract]
Contract with Customer, Liability, Current	3,147
Contract with Customer, Liability, Current, Net Increase (Decrease)	869
Contract with Customer, Liability, Current	4,016
Contract with Customer, Liability, Noncurrent [Abstract]
Contract with Customer, Liability, Noncurrent	1,834
Contract with Customer, Liability, Noncurrent, Net Increase (Decrease)	(103)
Contract with Customer, Liability, Noncurrent	$ 1,731