Supplementary Cash Flow Information (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Supplemental Cash Flow Elements [Abstract]

Schedule of Supplemental Cash Flow Information

The following supplemental cash flow information is provided with respect to certain non-cash investing and financing activities.

	Three months ended March 31,
	2018			2017
Cash paid for:
Interest	$	15		$	30
Income taxes	2			14
Non-cash investing and financing activities:
Investing activities:
Change in proceeds of sales of investments available for sale receivable in period	$	11		$	(9	)
Change in purchases of investments available for sale payable in period	(4		)	1
Financing activities:
Accrual for unsettled debt service payments related to the Notes	$	—		$	9
Accrual for the equity portion of unsettled repurchases of the Notes	—			12

The following supplemental cash flow information is provided with respect to interest and tax payments, as well as certain non-cash investing and financing activities.

	Year Ended December 31,
	2017			2016		2015
	(In millions)
Cash paid during the year:
Interest	$	102		$	125	$	124
Income taxes	528			367		250
Non-cash investing and financing activities:
Investing activities:
Change in proceeds of sales of investments available for sale receivable in period	$	3		$	7	$	(25	)
Change in purchases of investments available for sale payable in period	(9		)	19		(2		)
Financing activities:
Liabilities assumed in connection with acquisitions (1):
Fair value of net assets acquired	$	595		$	625	$	155
Less: Total purchase price	481			557		111
Liabilities and noncontrolling interests assumed	$	114		$	68	$	44
Change in treasury stock purchases payable in period	$	—		$	8	$	(7	)

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(1) See Note B Acquisitions for further discussion of assets and liabilities acquired in business combinations in the current year.