Consolidated Balance Sheets (Parenthetical) - USD ($) shares in Thousands, $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Accounts receivable, allowance	$ 1.0	$ 1.2
Restricted cash, current	32.0	37.0
Accumulated depreciation and amortization, property	777.2	741.0
Restricted cash, noncurrent	$ 71.6	$ 72.4
Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	10,000	10,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Series A Junior Participating Preferred Stock [Member]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	0	0
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Class A Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares issued (in shares)	336,736	335,452
Common stock, shares outstanding (in shares)	336,736	335,452
Class B Common Stock [Member]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	3	3
Common stock, shares issued (in shares)	3	3
Common stock, shares outstanding (in shares)	3	3