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Stock-Based Compensation Plans - Amendments to Restricted Stock and SARs - Additional Information (Detail) | 9 Months Ended
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Sep. 30, 2016
Restricted Stock Sales Restriction [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Sales restriction lapse percentage for restricted stock | 20.00%
Sales restriction period for restricted stock | 5 years
Employee termination age | 67 years
Percentage of shares of stock released from resale restriction upon consummation of change of control | 100.00%
Percentage of shares of restricted released from resale restriction in the event of death or termination after reaching age 67 | 100.00%
Deferred stock units [Member] |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Employee termination age | 67 years
DSU settlement to common stock percentage | 20.00%
DSU settlement into actual stock issued term | 5 years
Percentage of shares of deferred stock units settled in the event of death or termination after reaching age 67 | 100.00%

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