Debt and lines of credit (Tables)

12 Months Ended

Dec. 31, 2013

Debt Disclosure [Abstract]

Schedule of long-term debt Instruments

Long-term debt outstanding as of December 31, 2013 and 2012 is as follows:

	December 31,
	2013			2012
Floating-rate notes due 2013 (swapped to a 0.922% fixed rate)	$	—		$	1,000
Notes due 2013 at 0.875%	—			500
Notes due 2014 at 1.375%	1,000			1,000
Notes due 2015 at 3.95% (assumed with National acquisition)	250			250
Notes due 2015 at 0.45%	750			750
Notes due 2016 at 2.375%	1,000			1,000
Notes due 2017 at 6.60% (assumed with National acquisition)	375			375
Notes due 2018 at 1.00%	500			—
Notes due 2019 at 1.65%	750			750
Notes due 2023 at 2.25%	500			—
	5,125			5,625
Net unamortized premium	33			61
Current portion of long-term debt	(1,000		)	(1,500		)
Long-term debt	$	4,158		$	4,186