Share-Based Compensation - Schedule of Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Shares Under Option
Outstanding at beginning of period	3,707
Exercised	(22)
Cancelled/forfeited/expired	(1)
Outstanding at end of period	3,684	3,707
Vested and expected to vest at end of period	3,684
Exercisable at end of period	1,720
Weighted Average Exercise Price
Outstanding at beginning of period	$ 19.66
Exercised	13.23
Cancelled/forfeited/expired	13.23
Outstanding at end of period	19.70	$ 19.66
Vested and expected to vest at end of period	19.70
Exercisable at end of period	$ 9.84
Weighted Average Remaining Contractual Term (years)
Outstanding	3 years 4 months 24 days	3 years 7 months 6 days
Vested and expected to vest at end of period	3 years 4 months 24 days
Exercisable at end of period	4 years 3 months 18 days
Aggregate Intrinsic Value
Outstanding at beginning of period	$ 8.4
Outstanding at end of period	11.3	$ 8.4
Vested and expected to vest at end of period	11.3
Exercisable at end of period	$ 11.3