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Number of shares of common stock repurchased under the stock repurchase program over the life of the plan to date.

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Deferred compensation arrangement with non employee directors - number of option grants entitlement during period.

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Number of shares of common stock vested per each restricted stock unit when restrictions lapse and vesting conditions are met.

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Number of installments over which share based awards generally vest.

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Employee maximum elected percentage reduction of compensation to purchase shares pursuant to employee stock purchase plan.

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Share based compensation arrangement by share based payment award extended month and year.

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Required minimum holding period of shares acquired under employee stock purchase plan.

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Number of shares available for issuance of stock based awards under current plan, returned from previous plans.

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Duration of each purchase period under employee stock purchase plan.

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Required number of service hours per week to qualify to participate in Employee Stock Purchase Plan.

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Value divided by the fair market value of a share of common stock on the first day of the purchase period. The result of which is used to derive the maximum number of shares that may be purchased by each participant in a purchase period, pursuant to the employee stock purchase program.

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Aggregate dividends paid during the period for each share of common stock outstanding.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of paid and unpaid cash, stock, and paid-in-kind (PIK) dividends declared, for example, but not limited to, common and preferred stock.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Face amount or stated value per share of preferred stock nonredeemable or redeemable solely at the option of the issuer.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Number of additional shares authorized for issuance under an established share-based compensation plan.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

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Number of options outstanding, including both vested and non-vested options.

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Description of significant modifications (such as a change in expiration dating, vesting rights, or exercise prices) to an equity-based compensation plan, including the terms of the modifications.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Purchase price of common stock expressed as a percentage of its fair value.

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Amount of stock repurchase plan authorized.

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Stockholders' Equity - Additional Information (Detail)	3 Months Ended												12 Months Ended
Stockholders' Equity - Additional Information (Detail)	Dec. 31, 2016 USD ($) $ / shares shares	Sep. 30, 2016 $ / shares	Jun. 30, 2016 $ / shares	Mar. 31, 2016 $ / shares	Dec. 31, 2015 $ / shares shares	Sep. 30, 2015 $ / shares	Jun. 30, 2015 $ / shares	Mar. 31, 2015 $ / shares	Dec. 31, 2014 $ / shares	Sep. 30, 2014 $ / shares	Jun. 30, 2014 $ / shares	Mar. 31, 2014 $ / shares	Dec. 31, 2016 USD ($) $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) Installment $ / shares	Dec. 31, 2012 shares	Oct. 31, 2016 USD ($)	Jul. 31, 2015 USD ($)	Feb. 28, 2015 USD ($)	Dec. 31, 2011 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized	500,000				500,000								500,000	500,000
Preferred stock, par value \| $ / shares	$ 0.01				$ 0.01								$ 0.01	$ 0.01
Authorized to purchase of common stock under the stock repurchase program \| $	$ 485,000,000												$ 485,000,000				$ 25,000,000	$ 25,000,000	$ 25,000,000
Cumulative repurchase of common stock	15,000,000												15,000,000
Aggregate cost of repurchase of common stock \| $													$ 424,900,000
Dividend declared and paid per share \| $ / shares	$ 0.18	$ 0.18	$ 0.18	$ 0.18	$ 0.17	$ 0.17	$ 0.17	$ 0.17	$ 0.16	$ 0.16	$ 0.16	$ 0.16
Dividend declared per share \| $ / shares													$ 0.72	$ 0.68	$ 0.64
Aggregate dividend declared for the year \| $													$ 13,000,000	$ 12,200,000	$ 12,000,000
Option Outstanding and vested	1,540,000				2,171,000								1,540,000	2,171,000
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	200,000												200,000
Shares authorized	700,000												700,000
Hours of work per week													20 hours
Duration of purchase periods under employee stock purchase plan													6 months
Holding period of stocks acquired under employee stock purchase plan													1 year
Value used to derive maximum number of shares per participant for employee stock purchase \| $													$ 12,500
Employee maximum elected percentage reduction of compensation to purchase shares													10.00%
Exercise price rate of fair value													85.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value for RSUs granted \| $ / shares													$ 37.87	$ 31.50	$ 36.67
Number of shares received per restricted stock unit on lapse of restrictions and vesting condition met													1
Value of RSUs vested and converted to common stock \| $													$ 6,600,000	$ 4,600,000	$ 3,500,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Intrinsic value of options exercised \| $													$ 3,700,000	$ 400,000	$ 2,300,000
Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock options entitlement of non- employee directors	12,000												12,000
Number of installments upon which share based awards vest \| Installment															4
1996 Equity Plan [Member] \| Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	0												0
2006 Director Plan [Member] \| Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	0												0
Shares authorized	450,000,000												450,000,000
Shares returned																80,000
Number of shares of common stock options entitlement of non- employee directors																				6,000,000
Option Outstanding and vested	200,000												200,000
1996 Director [Member] \| Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	0												0
Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity incentive plan extended term													10 years
Equity incentive plan expiration													2026-05
Increase in number of shares issuable under plan													2,000,000
Equity Incentive Plan [Member] \| Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Future awards granted or issued under plans	2,700,000												2,700,000
Shares authorized																6,350,000
Shares returned																2,500,000
Option expiration period													10 years
Equity Incentive Plan [Member] \| Equity Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options vested period													4 years
Prior to 2011 [Member] \| Equity Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares of common stock options entitlement of non- employee directors	12,500												12,500