Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Summary of Significant Accounting Policies [Abstract]

Valuation of Option Grants under Stock Option Plans

	2018				2017				2016
Expected volatility	30.6	-	31.4	%	32.4	-	36.1	%	37.1	-	43.1	%
Weighted-average volatility	31.4%				36.1%				41.0%
Expected dividends	2.22	-	2.66	%	1.98	-	2.28	%	2.28	-	2.94	%
Risk-free rate	2.7	-	3.1	%	2.1	-	2.3	%	1.4	-	2.1	%
Expected term (in years)	7.4	-	7.4		7.4	-	7.4		7.4	-	7.4
Pre-vesting departure rate	0.6	-	0.6	%	0.6	-	0.6	%	0.6	-	0.6	%

Supplemental Disclosure of Cash Flow Information

	Years ended December 31,
	2018		2017		2016
Non-cash transactions:
Accruals for capital expenditures	$	412	$	584	$	381
Cash paid for interest and income taxes:
Interest(1)	$	205	$	178	$	184
Income taxes, net of refunds received	$	567	$	405	$	293

(1) Included in this amount are approximately $49 million, $36 million, and $23 million of interest costs that were capitalized as part of property, plant and equipment, net of accumulated depreciation, in 2018, 2017 and 2016, respectively.

Useful Life of Equipment

Asset type	Range of useful life
Computer hardware and software	3 to 7 years
Manufacturing equipment	2 to 15 years
Furniture and fixtures	5 to 10 years
Transportation equipment	3 to 20 years