Summary of Stock Option Activity (Detail) - Jun. 30, 2015 - Employee Stock Option - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	Total
Shares
Outstanding at December 31, 2014	2,816
Granted	712
Exercised	(190)
Forfeited and expired	(502)
Outstanding at June 30, 2015	2,836
Expected to vest at June 30, 2015	1,308
Exercisable at June 30, 2015	1,460
Weighted-Average Exercise Price
Outstanding at December 31, 2014	$ 29.51
Granted	23.61
Exercised	19.53
Forfeited and expired	34.24
Outstanding at June 30, 2015	27.86
Expected to vest at June 30, 2015	26.46
Exercisable at June 30, 2015	$ 29.25
Weighted-Average Remaining Contractual Term (years)
Outstanding at June 30, 2015	3 years 3 months
Expected to vest at June 30, 2015	4 years 8 months 5 days
Exercisable at June 30, 2015	1 year 10 months 10 days
Aggregate Intrinsic Value
Outstanding at June 30, 2015	$ 0.2
Expected to vest at June 30, 2015	0.0
Exercisable at June 30, 2015	$ 0.2