Summary of Stock Option Activity (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Shares Under Option
Outstanding at beginning of period	4,139
Exercised	(118)
Cancelled/forfeited/expired	(109)
Outstanding at end of period	3,912	4,139
Vested and expected to vest at end of period	3,885
Exercisable at end of period	1,395
Weighted Average Exercise Price
Outstanding at beginning of period	$ 19.39
Exercised	$ 10.39
Cancelled/forfeited/expired	$ 27.92
Outstanding at end of period	$ 19.43	$ 19.39
Vested and expected to vest at end of period	$ 19.47
Exercisable at end of period	$ 9.05
Weighted Average Remaining Contractual Term (years)
Outstanding	5 years 6 months	5 years 7 months 6 days
Vested and expected to vest at end of period	5 years 4 months 24 days
Exercisable at end of period	5 years 10 months 24 days
Aggregate Intrinsic Value
Outstanding at beginning of period	$ 21.2
Outstanding at end of period	14.8	21.2
Vested and expected to vest at end of period	14.7
Exercisable at end of period	$ 12.4