Common and preferred stock shares authorized.

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Pertains to the percentage of the lower of the market related to purchase of common stock permitted by employee stock purchase plan to be acquired by employees and employees of designated subsidiaries.

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Aggregate number of common shares reserved for future issuance.

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Face amount or stated value per share of common stock.

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The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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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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Total number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) issued to shareholders (includes related preferred shares that were issued, repurchased, and remain in the treasury). May be all or portion of the number of preferred shares authorized. Excludes preferred shares that are classified as debt.

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Aggregate share number for all nonredeemable preferred stock (or preferred stock redeemable solely at the option of the issuer) held by stockholders. Does not include preferred shares that have been repurchased.

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- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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- Definition

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

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- Definition

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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No definition available.

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- Definition

The highest percentage of annual salary that an employee is permitted to utilize with respect to the plan.

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- Definition

Number of additional shares authorized for issuance under share-based payment arrangement.

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No definition available.

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Number of shares authorized for issuance under share-based payment arrangement.

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- Definition

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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- Definition

The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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- Definition

Number of shares issued under share-based payment arrangement.

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- Definition

The remaining number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

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No definition available.

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Number of shares that have been repurchased and retired during the period.

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Total cost of shares repurchased divided by the total number of shares repurchased.

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Authorized shares of common and preferred stock and stock-based compensation plans (Details) - $ / shares			3 Months Ended		9 Months Ended
	Jan. 01, 2019	May 14, 2013	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	May 05, 2020	Dec. 31, 2019	May 14, 2019	May 12, 2015	May 11, 2010	May 31, 2005	Jan. 21, 2004
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Additional number of shares reserved for issuance (in shares)		180,000,000
Common stock, authorized (in shares)		360,000,000	360,000,000		360,000,000			360,000,000
Common and preferred stock shares authorized (in shares)		365,000,000
Preferred stock, authorized (in shares)		5,000,000	5,000,000		5,000,000			5,000,000
Preferred stock, par value per share (in usd per share)		$ 0.01	$ 0.01		$ 0.01			$ 0.01
Common stock, par value per share (in usd per share)		$ 0.01	$ 0.01		$ 0.01			$ 0.01
Number of shares reserved for issuance (in shares)										2,518,416	3,362,304
Preferred stock, issued (in shares)			0		0			0
Preferred stock, outstanding (in shares)			0		0			0
Common stock repurchased (in shares)			446,502	1,056,078	1,114,701	3,205,676
Common stock repurchased, average cost per share (in usd per share)			$ 34.86	$ 42.42	$ 35.21	$ 42.79
Authorized common stock available for repurchase (in shares)			1,885,299		1,885,299
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance-based stock units, vested in period (in shares)					144,647	92,809
Share-based compensation arrangement by share-based payment award, award requisite service period	3 years				3 years
Performance-based stock units, weighted average grant date fair value (in usd per share)			$ 61.00	$ 57.46	$ 61.00	$ 57.46
Incentive Plan (2005) \| Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance (in shares)												4,050,000
Incentive Plan (2005) \| Restricted Stock Plan \| One to three year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					3 years
Incentive Plan (2005) \| Restricted Stock Plan \| Three to Five year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					5 years
Incentive Plan (2005) \| Restricted Stock Plan \| Ten year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					10 years
Incentive Plan (2010)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance (in shares)										2,518,416
Incentive Plan (2010) \| Restricted Stock Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, authorized (in shares)											3,000,000
Incentive Plan (2010) \| Restricted Stock Plan \| One to three year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					3 years
Incentive Plan (2010) \| Restricted Stock Plan \| Three to Five year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					5 years
Incentive Plan (2010) \| Restricted Stock Plan \| Ten year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					10 years
Incentive Plan (2015)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance (in shares)							567,142			3,000,000
Shares available for grant under 2015 restricted stock plan (in shares)							567,142
Incentive Plan (2015) \| Restricted Stock Plan \| One to three year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					3 years
Incentive Plan (2015) \| Restricted Stock Plan \| Three to Five year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					5 years
Incentive Plan (2015) \| Restricted Stock Plan \| Ten year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					10 years
Incentive Plan (2015) \| Restricted Stock Plan \| Four year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					4 years
Incentive Plan (2020)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares reserved for issuance (in shares)							4,500,000
Shares available for grant under 2015 restricted stock plan (in shares)			5,141,465		5,141,465
Incentive Plan (2020) \| Restricted Stock Plan \| One to three year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					1 year
Incentive Plan (2020) \| Restricted Stock Plan \| Three to Five year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					3 years
Incentive Plan (2020) \| Restricted Stock Plan \| Four year vesting period
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period (in years)					4 years
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, authorized (in shares)									3,000,000
Percentage of the lower of the market related to purchase of common stock			85.00%		85.00%
Maximum employee subscription rate			15.00%		15.00%
Common stock reserved for future issuance under employee stock purchase plan (in shares)			3,321,597		3,321,597
Shares issued under employee stock purchase plan (in shares)					764,173
Weighted average purchase price of employees' purchase rights (in usd per share)					$ 32.67
Series A Preferred Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, authorized (in shares)													750,000