Share-Based Compensation - Additional Information (Detail) $ in Millions		12 Months Ended
	May 19, 2011 HoursPerWeek	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares	Dec. 31, 2012 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock purchase plan expense (less than 1 million) | $			$ 1.0	$ 1.0
Total compensation expense | $		$ 33.0	20.0	13.0
Income tax benefit | $		$ 11.0	$ 7.0	$ 5.0
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period		728,940	1,383,195
Unearned compensation costs related to awards granted | $		$ 45.0
Unearned compensation cost, expected to be recognized over period (years)		2 years 4 months 24 days
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unearned compensation cost, expected to be recognized over period (years)		4 years
Stock Option and Stock Appreciation Rights (SARs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		4 years
2011 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SARs outstanding		672,290
Expiration period (in years)		10 years
Expiration period, if employee is terminated involuntarily other than for cause (days)		90 days
Expiration period, if employee voluntarily terminates his or her employment (days)		30 days
Expiration period, if employee's employment terminates due to death, disability, or retirement (Years)		1 year
RSA | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
1997 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares outstanding and exercisable		7,655
2011 Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Minimum working hours per week | HoursPerWeek	20
Maximum percentage of compensation deductions	10.00%
Stock purchase plan expense (less than 1 million) | $		$ 1.0
2011 Stock Purchase Plan | Date Of The Grant
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of purchase price on fair market value	95.00%
2011 Stock Purchase Plan | Date Of Purchase
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of purchase price on fair market value	95.00%
2006 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period (in years)		10 years
Expiration period, if employee is terminated involuntarily other than for cause (days)		90 days
Expiration period, if employee voluntarily terminates his or her employment (days)		30 days
Expiration period, if employee's employment terminates due to death, disability, or retirement (Years)		1 year
Shares outstanding and exercisable		644,407
Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options outstanding		1,397,611	1,292,142	1,402,784	1,535,804
Shares outstanding and exercisable		736,075	586,344	520,426
Expiration period (in years)		10 years
Stock Appreciation Rights (SARs) | Vest Annually In Each Of First Four Anniversaries
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares expected to vest		332,159	195,560
2015 Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized for issuance of awards		4,000,000
Shares available for grant		3,430,707
Vesting in year one | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Vesting in year two | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Vesting in year three | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
Vesting in year four | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		25.00%
2015 Incentive Plan | Stock Appreciation Rights (SARs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
SARs outstanding		325,512