New Accounting Pronouncements - Additional Information (Detail) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Operating lease, Percentage of office facilities	96.00%
ASU 2018-02 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Reclassification between AOCI and 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