XML 150 R111.htm IDEA: XBRL DOCUMENT v3.6.0.2
Pensions and Other Benefits - Summary of Pension Plan Asset Allocation and Current Weighted Average Policy Range (Detail)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 100.00%  
Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation Percentage 100.00% 100.00%
Cash and Cash Equivalents [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 0.50%  
Cash and Cash Equivalents [Member] | Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation percentage, current policy lower range 0.00%  
Asset allocation percentage, current policy upper range 5.00%  
Asset allocation Percentage 1.10% 1.10%
Fixed Income Securities [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 29.50%  
Fixed Income Securities [Member] | Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation percentage, current policy lower range 20.00%  
Asset allocation percentage, current policy upper range 40.00%  
Asset allocation Percentage 21.40% 21.00%
Public equity [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 46.00%  
Public equity [Member] | Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation percentage, current policy lower range 35.00%  
Asset allocation percentage, current policy upper range 55.00%  
Asset allocation Percentage 53.80% 54.50%
Real estate and infrastructure [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 12.00%  
Real estate and infrastructure [Member] | Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation percentage, current policy lower range 4.00%  
Asset allocation percentage, current policy upper range 20.00%  
Asset allocation Percentage 7.50% 5.80%
Absolute Return [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Current asset allocation target 12.00%  
Absolute Return [Member] | Pension Plans, Defined Benefit [Member]    
Deferred Compensation Arrangement with Individual, Postretirement Benefits [Line Items]    
Asset allocation percentage, current policy lower range 0.00%  
Asset allocation percentage, current policy upper range 18.00%  
Asset allocation Percentage 16.20% 17.60%