Income Taxes - Unrecognized Tax Benefits (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
Income Taxes
Unrecognized tax benefits at the beginning of year	$ 2,223
Gross increases - current year tax positions	13,899
Gross increases - prior year tax positions
Gross decreases - prior year tax positions	(1,569)
Unrecognized tax benefits at end of year	14,553
Interest and penalties in year-end balance

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Amount of unrecognized tax benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 45
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Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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- Definition

Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

+ References

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-Publisher FASB
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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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-Name Accounting Standards Codification
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Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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