The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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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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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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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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Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable.

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Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Feb. 07, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Tax benefits recorded on stock based compensation	$ 18.9	$ 24.3
Aggregate intrinsic value of options exercisable	$ 576.7
Weighted average remaining contractual term of options exercisable (in years)	5 years 3 months 18 days
Minimum \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting provisions (in years)	1 year
Minimum \| Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting provisions (in years)	1 year
Maximum \| Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting provisions (in years)	5 years
Maximum \| Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Period of vesting provisions (in years)	3 years
Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized (in shares)			16,750,000	13,250,000