Deferred Revenue - Rollforward (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Deferred revenue
Balance at the beginning of the period	$ 364.3
Deferred cash collections	256.2
Revenue recognized from deferred revenue	(283.6)
Balance at the end of the period	336.9
U.S. Government | Enhanced View SLA
Deferred revenue
Balance at the beginning of the period	172.9
Deferred cash collections	150.0
Revenue recognized from deferred revenue	(168.6)
Balance at the end of the period	154.3
U.S. Government | Value Added Services
Deferred revenue
Balance at the beginning of the period	68.9
Deferred cash collections	29.5
Revenue recognized from deferred revenue	(29.5)
Balance at the end of the period	68.9
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	(7.6)
Balance at the end of the period	66.1
Diversified commercial | DAP
Deferred revenue
Balance at the beginning of the period	41.5
Deferred cash collections	40.4
Revenue recognized from deferred revenue	(45.0)
Balance at the end of the period	36.9
Diversified commercial | Other
Deferred revenue
Balance at the beginning of the period	7.3
Deferred cash collections	36.3
Revenue recognized from deferred revenue	(32.9)
Balance at the end of the period	$ 10.7