Basis of Presentation and Significant Accounting Policies - Summary of Table Reconciling Basic and Diluted Net Income Per Share (Parenthetical) (Detail) - shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock [Member]
Summary Of Computation Of Basic And Diluted Earnings Per Share [Line Items]
Antidilutive securities not included in the computation of net income per diluted share	8,000	3,000	0
Stock Options [Member]
Summary Of Computation Of Basic And Diluted Earnings Per Share [Line Items]
Antidilutive securities not included in the computation of net income per diluted share	100,000	500,000	700,000

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration