Stockholders' Equity (Deficit) (Details)	12 Months Ended
	Dec. 31, 2017 item $ / shares shares	Dec. 31, 2016 $ / shares shares
Stockholders’ Equity (Deficit)
Common stock, par value (in dollars per share) | $ / shares	$ 86.08
Preferred Stock, shares authorized	20,000,000
Preferred Stock, par value (in dollars per share) | $ / shares	$ 0.01
Class A common stock
Stockholders’ Equity (Deficit)
Common stock, shares authorized	1,600,000,000	1,600,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares outstanding	228,033,671	226,812,205
Votes per share	1
Class B common stock
Stockholders’ Equity (Deficit)
Common stock, shares authorized	800,000,000	800,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.01	$ 0.01
Common stock, shares outstanding	238,435,208	238,435,208
Votes per share	10
Number of shares of Class A common stock into which each share of common stock is convertible	1
Class C common stock
Stockholders’ Equity (Deficit)
Common stock, shares authorized	800,000,000
Common stock, par value (in dollars per share) | $ / shares	$ 0.01
Common stock, shares outstanding	0	0
Preferred Stock, shares outstanding	0	0
Votes per share	1
Number of shares of Class A common stock into which each share of common stock is convertible	1
Votes per share in the event of change of control | item	10