Investments Held in Rabbi Trust - Additional Information (Detail)	Dec. 31, 2015
Equity-Based Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Mutual funds held in rabbi trust	79.00%
Debt-Based Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Mutual funds held in rabbi trust	21.00%

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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