Stock-Based Compensation (Detail) - (Table 6) - USD ($)	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested at January 1	5,135,000	5,874,000
Non-vested at January 1 (in Dollars per share)	$ 18.42	$ 17.37
Granted	625,000	330,000
Granted (in Dollars per share)	$ 32.56	$ 30.84
Vested	(281,000)	(272,000)
Vested (in Dollars per share)	$ 26.03	$ 23.56
Forfeited	(15,000)	(14,000)
Forfeitures (in dollars per share)	$ 26.86	$ 25.09
Non-vested at March 31	5,464,000	5,918,000
Non-vested at March 31 (in Dollars per share)	$ 19.60	$ 17.81

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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Number of shares related to Restricted Stock Award forfeited during the period.

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Value of stock related to Restricted Stock Awards forfeited during the period.

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