Income Taxes - Unrecognized Tax Benefit (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits [Roll Forward]
Beginning Balance	$ 20,020	$ 18,945	$ 47,949
Decreases related to prior year tax positions			(1,657)
Increases related to prior year tax positions	256		2,505
Increases related to current year tax positions	1,958	5,902	1,259
Decreases related to settlements with taxing authorities	(461)	(228)	(31,111)
Decreases related to current year tax positions		(4,599)
Decrease related to expiration of statute of limitations	(3,221)
Ending Balance	$ 18,552	$ 20,020	$ 18,945

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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Amount of unrecognized tax benefits.

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

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

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