Incentive Plan - Summary of Stock Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of options outstanding (shares) | shares	2,424,032
Weighted average remaining contractual life, options outstanding (years)	4 years 10 months 24 days
Weighted average exercise price, options outstanding (usd per share)	$ 19.80
Number of options exercisable (shares) | shares	1,612,946
Weighted average remaining contractual life, options exercisable (years)	3 years 3 months 18 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 17.29
$8.45 to 12.95
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise prices lower limit (usd per share)	8.45
Exercise prices higher limit (usd per share)	$ 12.95
Number of options outstanding (shares) | shares	293,334
Weighted average remaining contractual life, options outstanding (years)	1 year 3 months 18 days
Weighted average exercise price, options outstanding (usd per share)	$ 9.78
Number of options exercisable (shares) | shares	290,334
Weighted average remaining contractual life, options exercisable (years)	1 year 3 months 18 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 9.76
12.95 to 17.45
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise prices lower limit (usd per share)	12.95
Exercise prices higher limit (usd per share)	$ 17.45
Number of options outstanding (shares) | shares	900,520
Weighted average remaining contractual life, options outstanding (years)	3 years 8 months 12 days
Weighted average exercise price, options outstanding (usd per share)	$ 15.45
Number of options exercisable (shares) | shares	765,149
Weighted average remaining contractual life, options exercisable (years)	3 years 3 months 18 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 15.13
17.45 to 21.95
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise prices lower limit (usd per share)	17.45
Exercise prices higher limit (usd per share)	$ 21.95
Number of options outstanding (shares) | shares	196,744
Weighted average remaining contractual life, options outstanding (years)	4 years 2 months 12 days
Weighted average exercise price, options outstanding (usd per share)	$ 17.98
Number of options exercisable (shares) | shares	196,744
Weighted average remaining contractual life, options exercisable (years)	4 years 2 months 12 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 17.98
21.95 to 26.45
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise prices lower limit (usd per share)	21.95
Exercise prices higher limit (usd per share)	$ 26.45
Number of options outstanding (shares) | shares	457,563
Weighted average remaining contractual life, options outstanding (years)	8 years 9 months 18 days
Weighted average exercise price, options outstanding (usd per share)	$ 24.99
Number of options exercisable (shares) | shares	34,570
Weighted average remaining contractual life, options exercisable (years)	4 years 9 months 18 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 23.18
26.45 to 30.95
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise prices lower limit (usd per share)	26.45
Exercise prices higher limit (usd per share)	$ 30.95
Number of options outstanding (shares) | shares	575,871
Weighted average remaining contractual life, options outstanding (years)	5 years 10 months 24 days
Weighted average exercise price, options outstanding (usd per share)	$ 28.21
Number of options exercisable (shares) | shares	326,149
Weighted average remaining contractual life, options exercisable (years)	4 years 7 months 6 days
Weighted average exercise price, options exercisable (in dollars per share)	$ 28.04