New Financial Accounting Pronouncements - Additional Information (Detail) - ASU 2016-09 [Member] - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2017	Jan. 01, 2017
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Discrete tax benefit	$ 0.4
Retained Earnings [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Cumulative effect adjustment to reduce retained earnings		$ 0.1

Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption.

No definition available.

Name:	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant