Receivables, net (Tables)

12 Months Ended

Dec. 31, 2015

Receivables, net

Receivables, net

	December 31,
($ in millions)	2015			2014
Trade receivables		7,197			7,715
Other receivables		665			701
Allowance		(258	)		(279	)
		7,604			8,137
Unbilled receivables, net:
Costs and estimated profits in excess of billings		3,385			4,087
Advance payments consumed		(928	)		(1,146	)
		2,457			2,941
Total		10,061			11,078

Reconciliation of changes in allowance for doubtful accounts

($ in millions)	2015			2014			2013
Balance at January 1,		279			317			271
Additions		118			103			147
Deductions		(113	)		(118	)		(92	)
Exchange rate differences		(26	)		(23	)		(9	)
Balance at December 31,		258			279			317