Stockholders' Equity - Summary of Stock Appreciation Rights Activity (Parenthetical) (Detail)	Sep. 30, 2015 $ / shares
Equity Incentive Plan [Member] \| Stock appreciation rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Closing stock price of common stock	$ 42.50

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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