Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended	12 Months Ended
	Apr. 25, 2013	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized			$ 2.6	$ 3.7	$ 3.0
Stock-based compensation expense after tax			$ 2.0	$ 2.5	$ 2.0
Weighted-average risk-free rate of return (as percent)			2.69%	1.95%	1.25%
Expected option life			5 years 3 months	5 years 3 months	5 years 3 months 18 days
Expected stock price volatility rate (as percent)			23.00%	24.90%	29.60%
Assumed dividend yield (as percent)			0.74%	0.60%	0.80%
Options outstanding (in shares)			790,744	1,339,106
Exercisable at end of year (in shares)			666,396
Weighted-average fair value of options granted (in dollars per share)			$ 11.62	$ 11.50	$ 7.84
Aggregate intrinsic value of options exercised			$ 20.6	$ 7.5	$ 5.0
Total unrecognized compensation cost of nonvested stock options			$ 0.9
Expected weighted-average period			2 years 7 months 9 days
Non-Vested Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized			$ 0.7
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense recognized			$ 1.6
Vesting period		4 years
Restricted stock granted (in shares)			49,561
Weighted average fair value, granted (in dollars per share)			$ 48.38	$ 47.05	$ 29.94
Total compensation cost to be recognized			$ 3.6
Weighted average remaining contractual term			2 years 7 months
Total fair value, vested			$ 1.6	$ 1.2	$ 1.4
Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-statutory stock options, granted (in shares)	750,000
Non-statutory stock options, vesting percentage after second year (as percent)	40.00%
Non-statutory stock options, vesting percentage in each of following three years (as percent)	20.00%
Non-statutory stock options, exercise price over December 2012 market value (as percent)	20.00%
Non eligibility period of receiving grants under any of other stock based award programs			5 years
Vesting period	3 years
Chief Executive Officer | Non-Plan Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average risk-free rate of return (as percent)			0.76%
Expected option life			5 years
Expected stock price volatility rate (as percent)			40.50%
Assumed dividend yield (as percent)			1.01%
Options outstanding (in shares)			376,177
Exercisable at end of year (in shares)			376,177
Share-based Compensation Award, Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vest in percentage per annum increments (as percent)			25.00%
Share-based Compensation Award, Tranche One | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance award vesting period			5 years
Share-based Compensation Award, Tranche One | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance award vesting period			7 years
Share-Based Compensation Award, Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vest in percentage per annum increments (as percent)				25.00%
Share-Based Compensation Award, Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vest in percentage per annum increments (as percent)					25.00%
Share-based Compensation Award, Tranche Four
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options granted, vest in percentage per annum increments (as percent)					25.00%
Stock Incentive 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for future grants under 2013 Plan (in shares)			1,500,000
Shares reserved for future issuance (in shares)			1,483,392
Stock Incentive 2013 Plan | Executive Officers
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Incentive stock options issued (in shares)						450,000