Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 3.2	$ 2.9
Property and equipment, accumulated depreciation (in dollars)	831.2	676.2
Intangible assets, accumulated amortization (in dollars)	6.1	0
Aerial image library, accumulated amortization (in dollars)	$ 39.3	$ 33.4
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	250.0	250.0
Common stock, shares issued	75.4	47.2
Common stock, shares outstanding	75.2	47.1
Treasury stock, shares	0.2	0.1
Preferred stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	24.00	24.00
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Series A Convertible Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	0.08	0
Preferred stock, shares issued	0.08	0
Preferred stock, shares outstanding	0.08	0