Restructuring and Other Costs (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Sep. 30, 2016
Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       $ 201  
Net pre-tax restructuring costs (reversals) $ 32        
Cost of Sales [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       110  
Selling, General and Administrative Expenses [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       65  
Other Expense [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       26  
Current Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       143  
Restructuring Reserve 99 $ 87   99  
Net pre-tax restructuring costs (reversals) 30 85 $ 28 143  
Utilization and foreign exchange 18     44  
Expected Costs 242     242  
Remaining Costs 99     99  
Current Year Actions [Member] | Cost of Sales [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       71  
Current Year Actions [Member] | Selling, General and Administrative Expenses [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       46  
Current Year Actions [Member] | Severance [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Reserve 37 27   37  
Net pre-tax restructuring costs (reversals) 22     71  
Utilization and foreign exchange 12     34  
Current Year Actions [Member] | Facility Exit, Lease Termination and Other Costs          
Restructuring Cost and Reserve [Line Items]          
Restructuring Reserve 62 60   62  
Net pre-tax restructuring costs (reversals) 8     72  
Utilization and foreign exchange 6     10  
Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       44  
Restructuring Reserve 91 138   91 $ 206
Net pre-tax restructuring costs (reversals) (9) 24 29 44 326
Utilization and foreign exchange 38     159  
Expected Costs 473     473  
Remaining Costs 103     103  
Prior Year Actions [Member] | Cost of Sales [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       35  
Prior Year Actions [Member] | Selling, General and Administrative Expenses [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       9  
Prior Year Actions [Member] | Severance [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Reserve 63 113   63 183
Net pre-tax restructuring costs (reversals) (14)     23  
Utilization and foreign exchange 36     143  
Prior Year Actions [Member] | Facility Exit, Lease Termination and Other Costs          
Restructuring Cost and Reserve [Line Items]          
Restructuring Reserve 28 25   28 23
Net pre-tax restructuring costs (reversals) 5     21  
Utilization and foreign exchange 2     16  
Two Years Prior Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Reserve 42     42  
Otis [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       41  
Otis [Member] | Current Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 9 13 10    
Expected Costs 38     38  
Remaining Costs 6     6  
Otis [Member] | Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 2 5 5   35
Expected Costs 51     51  
Remaining Costs 4     4  
UTC Climate, Controls & Security [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       71  
UTC Climate, Controls & Security [Member] | Current Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 13 8 13    
Expected Costs 53     53  
Remaining Costs 19     19  
UTC Climate, Controls & Security [Member] | Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 5 14 14   83
Expected Costs 195     195  
Remaining Costs 79     79  
Pratt & Whitney [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       50  
Pratt & Whitney [Member] | Current Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 0 61 0    
Expected Costs 61     61  
Remaining Costs 0     0  
Pratt & Whitney [Member] | Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) (24) 0 1   82
Expected Costs 59     59  
Remaining Costs 0     0  
UTC Aerospace Systems [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       32  
UTC Aerospace Systems [Member] | Current Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 8 3 5    
Expected Costs 90     90  
Remaining Costs 74     74  
UTC Aerospace Systems [Member] | Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 3 4 8   105
Expected Costs 140     140  
Remaining Costs 20     20  
Eliminations and other [Member]          
Restructuring Cost and Reserve [Line Items]          
Restructuring Charges       7  
Eliminations and other [Member] | Prior Year Actions [Member]          
Restructuring Cost and Reserve [Line Items]          
Net pre-tax restructuring costs (reversals) 5 $ 1 $ 1   $ 21
Expected Costs 28     28  
Remaining Costs $ 0     $ 0