Revenue - Narrative (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Performance obligation unsatisfied or partially satisfied	$ 145,900,000		$ 145,900,000
Capitalized cost, impairment	0	$ 0	0	$ 0
Contract cost, accumulated amortization	$ 4,400,000		$ 4,400,000		$ 9,200,000