Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017
Operating Loss Carryforwards [Line Items]
Estimated Annual Effective Tax Rate	34.00%	36.00%
Proceeds and Excess Tax Benefit from Share-based Compensation			$ 1.0

The aggregate cash inflow comprised of the amount received from (a) employees to acquire the entity's shares under incentive awards, including stock option exercises and restricted stock arrangements, and (b) the excess tax benefit arising from such transactions.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration