Related Party Transactions - Summary of Royalty Revenue Recognized (Parenthetical) (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Related Party Transactions [Abstract]
Earned fees	$ 0.8	$ 0.7	$ 1.6	$ 1.3