Summary of Stock Option Activity (Detail) (Employee Stock Option, USD $) In Millions, except Share data in Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Employee Stock Option
Shares
Outstanding at December 31, 2013	2,698
Granted	749
Exercised	(265)
Forfeited and expired	(340)
Outstanding at Sept. 30, 2014	2,842
Expected to vest at Sept. 30, 2014	1,346
Exercisable at Sept. 30, 2014	1,463
Weighted-Average Exercise Price
Outstanding at December 31, 2013	$ 32.74
Granted	$ 32.26
Exercised	$ 14.06
Forfeited and expired	$ 72.90
Outstanding at Sept. 30, 2014	$ 29.55
Expected to vest at Sept. 30, 2014	$ 27.38
Exercisable at Sept. 30, 2014	$ 31.56
Weighted-Average Remaining Contractual Term (years)
Outstanding at Sept. 30, 2014	2 years 7 months 13 days
Expected to vest at Sept. 30, 2014	3 years 8 months 27 days
Exercisable at Sept. 30, 2014	1 year 6 months 18 days
Aggregate Intrinsic Value
Outstanding at Sept. 30, 2014	$ 2.2
Expected to vest at Sept. 30, 2014	0.9
Exercisable at Sept. 30, 2014	$ 1.3