Debt and Lines of Credit (Tables)

12 Months Ended

Dec. 31, 2016

Debt Disclosure [Abstract]

Schedule of Long-term Debt Instruments

Long-term debt outstanding is as follows:

	December 31,
	2016			2015
Notes due 2016 at 2.375%	$	—		$	1,000
Notes due 2017 at 0.875%		250			250
Notes due 2017 at 6.60% (assumed with National acquisition)		375			375
Notes due 2018 at 1.00%		500			500
Notes due 2019 at 1.65%		750			750
Notes due 2020 at 1.75%		500			500
Notes due 2021 at 2.75%		250			250
Notes due 2022 at 1.85%		500			—
Notes due 2023 at 2.25%		500			500
Total debt		3,625			4,125
Net unamortized discounts, premiums and debt issuance costs		(16	)		(5	)
Total debt, including net unamortized discounts, premiums and    debt issuance costs		3,609			4,120
Current portion of long-term debt		(631	)		(1,000	)
Long-term debt	$	2,978		$	3,120