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Restricted Stock, Performance Share and Cash Awards - Additional Information (Detail)			3 Months Ended
	Mar. 14, 2019 USD ($) shares	Mar. 15, 2018 USD ($) shares	Mar. 31, 2019 USD ($) Times shares	Mar. 31, 2018 USD ($) shares	Mar. 31, 2017 shares	Mar. 31, 2016	Dec. 31, 2018 shares	Mar. 16, 2017 USD ($) shares	Mar. 17, 2016 USD ($) shares
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Share-based compensation, shares outstanding | shares			9,300,000				8,800,000
Shares granted in the period | shares			399,900	420,200
Long Term Incentive Plan [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Share-based compensation, shares outstanding, Value			$ 4,000,000
Share-based compensation, shares outstanding | shares			2,800,000
Shares granted in the period | shares			2,800,000
Restricted Stock Units (RSUs) [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Shares granted in the period | shares			399,900	420,200
Fair value of grants in period			$ 31,800,000	$ 28,700,000
Share based payment award vesting date			Mar. 14, 2024	Mar. 15, 2023
Restricted stock or unit expense			$ 6,400,000	$ 6,500,000
Unvested Restricted Stock [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Total intrinsic value			142,200,000	121,900,000
Equity awards with an aggregate fair value				21,200,000
Performance Shares [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Equity awards with an aggregate fair value			$ 5,700,000	3,700,000
Shares authorized | shares	73,600	78,200
Performance unit awards approved, Fair value	$ 5,800,000	$ 5,300,000
Provisional awards, terms			Granted units for the 2019 and 2018 provisional awards will fully vest based on continuous employment through March 14, 2022 and March 15, 2021, respectively, and will be settled in shares of our common stock on a one-for-one basis as soon as practicable thereafter.
Performance awards period, years			1 year
Vesting period, years			2 years
2019 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Performance awards expiration date			Jan. 01, 2022
Cash-based compensation awards, expenses			$ 1,900,000
2017 Performance Share Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional awards, terms			The 2019 and 2018 awards are subject to a three-year performance period that begins on January 1, 2019 and 2018, respectively, and vest on the three-year anniversary of the date of grant (March 14, 2022 and March 15, 2021).
Performance awards period, years			3 days
Vesting period, years			3 years
Performance awards expiration date			Mar. 14, 2022
2017 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Performance awards expiration date			Jan. 01, 2020
Cash-based compensation awards, expenses			$ 2,400,000	2,000,000
2016 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Performance awards expiration date					Jan. 01, 2019
Provisional compensation cash award approved for future grant by compensation committee, units | shares			341,000
Cash-based compensation awards, expenses			$ 22,400,000	$ 4,200,000
2015 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Performance awards expiration date						Jan. 01, 2019
Provisional compensation cash award approved for future grant by compensation committee, units | shares				269,000
Cash-based compensation awards, expenses				$ 15,800,000
Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Period of service from grant date stock options awarded not subject to forfeiture			2 years
Officer and Key Employees [Member] | Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional awards, terms			The ultimate award value will be equal to the trailing twelve-month price of our common stock on December 31, 2021, multiplied by the number of units subject to the award, but limited to between 0.5 and 1.5 times the original value of the units determined as of the grant date.
Performance awards period, years			1 year
Vesting period, years			3 years
Provisional compensation cash awards approved for future grant by compensation committee, value	$ 16,500,000	$ 15,000,000						$ 14,300,000
Provisional compensation cash award approved for future grant by compensation committee, units | shares	206,800	219,000	190,000	242,000				255,000
Ultimate award value, multiples of original value of the units, minimum | Times			0.5
Ultimate award value, multiples of original value of the units, maximum | Times			1.5
Officer and Key Employees [Member] | 2016 Provisional Cash Awards [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Provisional compensation cash awards approved for future grant by compensation committee, value									$ 17,400,000
Provisional compensation cash award approved for future grant by compensation committee, units | shares					383,000				397,000
Executive Officer [Member] | Minimum [Member] | Restricted Stock Units (RSUs) [Member]
Common Stock Options Restricted Stock Warrants And Changes In Capitalization [Line Items]
Minimum age of employee with not subject to award forfeiture on condition compliance			55 years	55 years

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