Stock-Based Compensation Assumptions Used (Detail) - Stock Options |
3 Months Ended | 12 Months Ended | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Mar. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
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| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||
| Weighted average volatility | 21.00% | [1] | 24.30% | [2] | 24.30% | [2] | 22.40% | [2] | ||||||
| Dividend yield | 0.50% | 0.60% | [3] | 0.60% | [3] | 0.50% | [3] | |||||||
| Minimum [Member] | ||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||
| Risk-free interest rate | 1.95% | 1.21% | 1.60% | 1.70% | ||||||||||
| Expected years until exercise | 5 years 6 months | 5 years 6 months | 5 years 6 months | 5 years 6 months | ||||||||||
| Maximum [Member] | ||||||||||||||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||||||||||||||
| Risk-free interest rate | 2.26% | 1.77% | 2.20% | 2.40% | ||||||||||
| Expected years until exercise | 8 years | 8 years | 8 years | 8 years | ||||||||||
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