Employee Stock Benefit Plans - Share-based Compensation, Award Activity (Details) - $ / shares shares in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options Outstanding, Number of Shares:
Stock options granted (in shares)	0
Stock options exercised (in shares)	(948)
Stock options canceled (in shares)	(41)
Stock Options Outstanding, Weighted Average Exercise Price Per Share:
Stock options, outstanding, weighted average exercise price, beginning of period (USD per share)	$ 3.79
Stock options granted, weighted average exercise price (USD per share)	0		$ 6.46
Stock options exercised, weighted average exercise price (USD per share)	2.62
Stock options canceled, weighted average exercise price (USD per share)	4.04
Stock options, outstanding, weighted average exercise price, end of period (USD per share)	$ 4.01	$ 3.79
Stock options, exercisable (in shares)	4,425
Stock options, exercisable, weighted average exercise price (USD per share)	$ 3.73
Restricted Stock and Restricted Stock Units, Number of Shares:
Restricted stocks and restricted stock units, outstanding, beginning of period (in shares)	9,906
Restricted stocks and restricted stock units, granted (in shares)	7,696
Restricted stocks and restricted stock units, exercised (in shares)	(4,917)
Restricted stocks and restricted stock units, canceled (in shares)	(2,296)
Restricted stocks and restricted stock units, outstanding, end of period (in shares)	10,389	9,906
Restricted Stock and Restricted Stock Units, Weighted Average Grant Date Fair Market Value Per Share:
Restricted stocks and restricted stock units, outstanding, weighted average exercise price, beginning of period (USD per share)	$ 8.81
Restricted stocks and restricted stock units, granted, weighted average exercise price (USD per share)	11.29	$ 10.55	$ 6.79
Restricted stocks and restricted stock units, exercised, weighted average exercise price (USD per share)	6.69
Restricted stocks and restricted stock units, canceled, weighted average exercise price (USD per share)	10.31
Restricted stocks and restricted stock units, outstanding, weighted average exercise price, end of period (USD per share)	$ 10.58	$ 8.81

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

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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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 non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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For presentations that combine terminations, the number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan or that expired.

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Weighted average price of options that were either forfeited or expired.

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Gross number of share options (or share units) granted during the period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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Number of share options (or share units) exercised during the current period.

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