Summary of Stock Option Activity (Detail) (Employee Stock Option, USD $) In Millions, except Share data in Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014
Employee Stock Option
Shares
Outstanding at December 31, 2013	2,698
Granted	745
Exercised	(232)
Forfeited and expired	(132)
Outstanding at March 31, 2014	3,079
Expected to vest at March 31, 2014	1,446
Exercisable at March 31, 2014	1,579
Weighted-Average Exercise Price
Outstanding at December 31, 2013	$ 32.74
Granted	$ 32.30
Exercised	$ 13.24
Forfeited and expired	$ 137.32
Outstanding at March 31, 2014	$ 29.65
Expected to vest at March 31, 2014	$ 27.24
Exercisable at March 31, 2014	$ 31.88
Weighted-Average Remaining Contractual Term (years)
Outstanding at March 31, 2014	3 years 1 month 6 days
Expected to vest at March 31, 2014	4 years 2 months 19 days
Exercisable at March 31, 2014	2 years 11 days
Aggregate Intrinsic Value
Outstanding at March 31, 2014	$ 11.2
Expected to vest at March 31, 2014	6.0
Exercisable at March 31, 2014	$ 5.1