Deferred Revenue - Rollforward (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($)
Deferred revenue
Balance at the beginning of the period	$ 364.3
Deferred revenue acquired	0.7
Deferred cash collections	497.7
Revenue recognized from deferred revenue	(559.5)
Balance at the end of the period	303.2
U.S. Government | Enhanced View SLA
Deferred revenue
Balance at the beginning of the period	172.9
Deferred cash collections	300.0
Revenue recognized from deferred revenue	(337.1)
Balance at the end of the period	135.8
U.S. Government | Value Added Services
Deferred revenue
Balance at the beginning of the period	68.9
Deferred revenue acquired	0.7
Deferred cash collections	55.1
Revenue recognized from deferred revenue	(60.6)
Balance at the end of the period	64.1
U.S. Government | Pre-FOC Payments Related To NextView
Deferred revenue
Balance at the beginning of the period	73.7
Revenue recognized from deferred revenue	(15.1)
Balance at the end of the period	58.6
Diversified commercial | DAP
Deferred revenue
Balance at the beginning of the period	41.5
Deferred cash collections	76.0
Revenue recognized from deferred revenue	(80.3)
Balance at the end of the period	37.2
Diversified commercial | Other
Deferred revenue
Balance at the beginning of the period	7.3
Deferred cash collections	66.6
Revenue recognized from deferred revenue	(66.4)
Balance at the end of the period	$ 7.5