Unaudited Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 20.8	$ 3.1
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization expense	137.9	136.0
Stock-based compensation expense, net of capitalized stock-based compensation expense	8.3	9.5
Amortization of aerial image library, deferred contract costs and lease incentive	8.4	8.8
Deferred income taxes	14.0	(1.0)
Excess tax benefit from share-based compensation	(0.1)	(1.3)
Amortization of debt issuance costs and accretion of debt discount, net of capitalized interest	6.0	3.3
Changes in working capita
Accounts receivable, net	(8.5)	29.4
Deferred contract costs	(8.0)	(10.3)
Other current and non-current assets	(2.4)	5.2
Accounts payable	3.7	(0.9)
Accrued liabilities	(4.1)	10.3
Deferred revenue	(27.4)	(40.2)
Net cash flows provided by operating activities	148.6	151.9
CASH FLOWS FROM INVESTING ACTIVITIES:
Construction in progress additions	(85.6)	(64.5)
Property and equipment additions	(0.2)	(1.9)
Decrease (increase) in restricted cash	0.5	(0.8)
Investment in joint venture	(7.5)	(5.0)
Net cash flows used in investing activities	(92.8)	(72.2)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of debt and capital lease obligations	(3.9)	(3.2)
Repurchase of common stock	(76.8)	(63.8)
Proceeds from exercise of stock options	1.2	5.2
Preferred stock dividend payment	(2.0)	(2.0)
Excess tax benefit from share-based compensation	0.1	1.3
Net cash flows used in financing activities	(81.4)	(62.5)
Net (decrease) increase in cash and cash equivalents	(25.6)	17.2
Cash and cash equivalents, beginning of period	126.1	117.8
Cash and cash equivalents, end of period	100.5	135.0
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest, net of capitalized amounts of $21.8 and $15.9 million, respectively	7.4	13.8
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Changes to non-cash property, equipment and construction in progress accruals, including interest	0.4	0.4
Non-cash preferred stock dividend accrual	$ (1.0)	$ (1.0)