Summary of Significant Accounting Policies - Stock Split (Details) $ in Millions		12 Months Ended
Feb. 21, 2018	Dec. 31, 2020 USD ($)
Class of Stock [Line Items]
Stock split ratio	2
Common Stock
Class of Stock [Line Items]
(Increase)/Decrease adjustments due stock split, APIC		$ (4)
Additional Paid-In Capital
Class of Stock [Line Items]
(Increase)/Decrease adjustments due stock split, APIC		$ 4

Amount of decrease in additional paid in capital (APIC) resulting from a stock split in which per-share par value or stated value is not changed proportionately.

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Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

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