Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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Percentage of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations applicable to state and local income tax expense (benefit), net of federal tax expense (benefit).

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The total recognized tax benefit related to compensation cost for equity-based payment arrangements recognized in income during the period.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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Income taxes.

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Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018
Income Taxes [Line Items]
Income tax expense (benefit)	$ 11,644	$ 16,172
Effective tax rate	22.50%	34.10%
Effect of reporting discrete items during the period	3.10%
Excess tax benefits from discrete items	$ 1,800	$ 800
Income tax expense credit	$ 1,200
Statutory Effective Tax Rate [Member]
Income Taxes [Line Items]
Effective tax rate	24.70%
State income tax rate, net of federal benefit	3.70%
U.S. federal statutory rate	21.00%
Forecast [Member]
Income Taxes [Line Items]
Effective tax rate			25.60%