Stock-Based Compensation (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013
Restricted Stock Awards
Number of Shares
Non-vested at the beginning of the period (in shares)	0.6
Granted in GeoEye acquisition (in shares)	0.5
Forfeited/Canceled (in shares)	(0.1)
Vested (in shares)	(0.5)
Non-vested at the end of the period (in shares)	0.5
Weighted-Average Exercise Price
Non-vested at the beginning of the period (in dollars per share)	$ 17.52
Granted in GeoEye acquisition (in dollars per share)	$ 27.97
Forfeited/Canceled (in dollars per share)	$ 24.00
Vested (in dollars per share)	$ 24.79
Non-vested at the end of the period (in dollars per share)	$ 19.13
Restricted Stock Units
Number of Shares
Non-vested at the beginning of the period (in shares)	0.1
Granted (in shares)	0.8
Granted in GeoEye acquisition (in shares)	0.3
Vested (in shares)	(0.4)
Non-vested at the end of the period (in shares)	0.8
Weighted-Average Exercise Price
Non-vested at the beginning of the period (in dollars per share)	$ 32.92
Granted (in dollars per share)	$ 30.72
Granted in GeoEye acquisition (in dollars per share)	$ 27.97
Vested (in dollars per share)	$ 28.04
Non-vested at the end of the period (in dollars per share)	$ 28.11
Restricted Stock Units | Performance share units
Number of Shares
Non-vested at the end of the period (in shares)	0.2
Restricted Stock Units | Performance share units - stock market condition
Weighted-Average Exercise Price
Granted (in dollars per share)	$ 47.32