Income Taxes - Summary of Reconciliation of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Gross Unrecognized Tax Benefits
Beginning balance	$ 4,238	$ 16,144	$ 19,892
Additions based on tax positions related to prior years	0	1,121	3,958
Settlements with taxing authorities	0	(13,027)	(4,820)
Reductions due to expiration of statute of limitations	(4,238)	0	(2,886)
Ending balance	$ 0	$ 4,238	$ 16,144

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

No definition available.

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- Definition

Amount of unrecognized tax benefits.

+ References

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-Publisher FASB
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- Definition

Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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- Definition

Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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