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Stock-Based Compensation - Summary of Characteristics of Options Outstanding (Detail) - 12 months ended Dec. 31, 2015 $ in Millions | USD ($) CAD / shares shares | CAD / shares
--- | --- | ---
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Number of options | 7,349,416 |
Remaining contractual life [years] | 4 years 11 days |
Number of options exercisable | 4,193,359 |
Aggregate intrinsic value | $ | $ 93 |
Weighted average exercise price of options | CAD / shares |  | CAD 38.59
Weighted average exercise price | CAD / shares |  | CAD 25.53
Weighted average life remaining [years], exercisable | 2 years 11 months 9 days |
Aggregate intrinsic value of options exercisable | $ | $ 93 |
Range One [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price range lower limit | CAD / shares | $ 10 |
Exercise price range upper limit | CAD / shares | $ 15 |
Number of options | 1,000,682 |
Remaining contractual life [years] | 10 months 24 days |
Number of options exercisable | 1,000,682 |
Range Two [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price range lower limit | CAD / shares | $ 15 |
Exercise price range upper limit | CAD / shares | $ 20 |
Number of options | 20,000 |
Remaining contractual life [years] | 1 year 4 months 24 days |
Number of options exercisable | 20,000 |
Range Three [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price range lower limit | CAD / shares | $ 20 |
Exercise price range upper limit | CAD / shares | $ 25 |
Number of options | 1,480,560 |
Remaining contractual life [years] | 3 years 2 months 12 days |
Number of options exercisable | 1,487,226 |
Range Four [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price range lower limit | CAD / shares | $ 25 |
Exercise price range upper limit | CAD / shares | $ 30 |
Number of options | 1,877,018 |
Remaining contractual life [years] | 3 years 9 months 18 days |
Number of options exercisable | 1,247,757 |
Range Five [Member] |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |
Exercise price range lower limit | CAD / shares | $ 50 |
Number of options | 2,971,156 |
Remaining contractual life [years] | 5 years 8 months 12 days |
Number of options exercisable | 437,694 |

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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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