Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Class A Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	138,922,000	138,594,000
Common stock, shares outstanding	138,922,000	138,594,000
Class B Common Stock [Member]
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	15,840,000	15,840,000
Common stock, shares outstanding	15,840,000	15,840,000