CONSOLIDATED AND COMBINED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	49,246,087	0
Common stock, shares outstanding	49,235,528	0
Class B common stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000	1,000,000
Common stock, shares issued	359,056	0
Common stock, shares outstanding	359,056	0