Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Weighted average lease term	3 years
Discount rate	4.00%
Annual payments to be received	$ 6
Maximum financing available		$ 380
Total costs incurred under lease	$ 47
Term of contract	5 years
Residual value guarantee		89.00%