Share-Based Compensation - Schedule of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / shares shares
Options
Stock options outstanding beginning of period (in shares)	2,258,000
Stock options granted (in shares)	0
Stock options exercised (in shares)	(1,051,000)
Stock options forfeited (in shares)	(272,000)
Stock options outstanding end of period (in shares)	935,000
Stock options exercisable at end of period (in shares)	679,000
Weighted Average Exercise Price
Stock options outstanding, Weighted Average Exercise Price, beginning of period (in dollars per share) | $ / shares	$ 40.63
Stock options exercised, Weighted Average Exercise Price (in dollars per share) | $ / shares	39.55
Stock options forfeited, Weighted Average Exercise Price (in dollars per share) | $ / shares	58.93
Stock options outstanding, Weighted Average Exercise Price, end of period (in dollars per share) | $ / shares	36.50
Stock options exercisable, end of period, Weighted Average Exercise Price (in dollars per share) | $ / shares	$ 36.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Stock options outstanding, Weighted Average Remaining Contractual Term (in Years)	5 years
Stock options exercisable, Weighted Average Remaining Contractual Term (in Years)	4 years 6 months
Stock options outstanding, Aggregate Intrinsic Value | $	$ 28,181
Stock options exercisable, Aggregate Intrinsic Value | $	$ 20,401