Summary of Significant Accounting Policies - Earnings Per Share (Detail) - shares |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2018 |
Sep. 30, 2017 |
Sep. 30, 2018 |
Sep. 30, 2017 |
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| Accounting Policies [Abstract] | ||||
| Number of shares of common stock received for each exchangeable share (in shares) | 1 | |||
| Weighted average shares outstanding attributable to participating securities (in shares) | 2,600,000 | 2,300,000 | 2,500,000 | 2,500,000 |
| X | ||||||||||
- Definition Number of shares of common stock received for each exchangeable share. No definition available.
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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