Stockholders' Equity - Additional Information (Detail) - shares	Dec. 31, 2016	Dec. 31, 2015
Equity [Abstract]
Shares reserved for issuance under the Directors Deferred Fee Plan	253,413	229,679

Number of common shares reserved for future issuance related to deferred compensation arrangements with individuals.

No definition available.

Name:	us-gaap_DeferredCompensationArrangementWithIndividualCommonStockReservedForFutureIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant