Incentive Award Plan - Shares Tendered (Detail) - shares	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares tendered for tax withholding requirements	36,374	12,670	6,928

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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