Stock Options - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2017 USD ($) $ / shares shares
Shares
Granted (in shares)	0
Employee Stock Options
Shares
Outstanding at beginning of period (in shares)	2,099,000
Granted (in shares)	0
Exercised (in shares)	(1,000)
Forfeited and expired (in shares)	(306,000)
Outstanding at end of period (in shares)	1,792,000
Expected to vest at end of period (in shares)	211,000
Exercisable at end of period (in shares)	1,574,000
Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share) | $ / shares	$ 25.41
Granted (in dollars per share) | $ / shares	0.00
Exercised (in dollars per share) | $ / shares	10.65
Forfeited and expired (in dollars per share) | $ / shares	20.04
Outstanding at end of period (in dollars per share) | $ / shares	26.33
Expected to vest at end of period (in dollars per share) | $ / shares	22.72
Exercisable at end of period (in dollars per share) | $ / shares	$ 26.84
Weighted- Average Remaining Contractual Term (years)
Outstanding at end of period	2 years 1 month 2 days
Expected to vest at end of period	4 years
Exercisable at end of period	1 year 9 months 25 days
Aggregate Intrinsic Value
Outstanding at end of period | $	$ 0.0
Expected to vest at end of period | $	0.0
Exercisable at end of period | $	$ 0.0