Stock-Based Compensation - RSUs to be Settled in Common Stock (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Non-cash stock compensation expense	$ 14,912	$ 13,012
Restricted Stock Units to be Settled in Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)	1.9	1.5
Weighted average grant date fair value (in dollars per share)	$ 39.07	$ 35.85
Vesting period for RSUs to be settled in stock	3 years
RSUs vested (in shares)	1.1	1.2
Fair value of restricted stock, vested	$ 43,700	$ 41,500
Non-cash stock compensation expense	12,000	$ 11,300
Unrecognized compensation cost, related to unvested RSUs to be settled in common stock, total	$ 113,800
Expected weighted average period to recognize compensation cost on RSUs to be settled in common stock	2 years 9 months 7 days

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of noncash expense for share-based payment arrangement.

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

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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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