Equity Plans (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deemed repurchases of restricted stock/units	$ 15,354	$ 12,796
Share-based compensation expense	$ 15,319	$ 12,464
Total unrecognized share-based compensation costs, remaining period of recognition (in years)	2 years 8 months
Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
New shares of Company's Class A common stock issued	418,069
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares surrendered to the Company for tax withholding	289,555
Total unrecognized share-based compensation costs	$ 133,800
Restricted Stock Units (RSUs) [Member] \| Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares vested in period	707,624
2016 Employee Stock Plan [Member] \| Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	684,737
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
2016 Employee Stock Plan [Member] \| Restricted Stock Units (RSUs) [Member] \| Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	195,028
2016 Employee Stock Plan [Member] \| Performance Vesting Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	537,403
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	3 years
2016 Employee Stock Plan [Member] \| Performance Vesting Options [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	0.00%
2016 Employee Stock Plan [Member] \| Performance Vesting Options [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	200.00%

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Unrecognized cost of unvested share-based compensation awards.

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Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Amount of cash outflow to reacquire equity classified as other.

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

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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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Percentage of vesting of share-based compensation awards.

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For net-share settlement of share-based awards when the employer settles employees' income tax withholding obligations, this element represents the number of shares the employees use to repay the employer.

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Total number of shares issued during the period, including shares forfeited, as a result of Restricted Stock Awards.

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