Mergers and Acquisitions (Tables)

12 Months Ended

Dec. 31, 2017

Acquisitions and Dispositions [Abstract]

Merger-related costs

	2017				2016				2015
(In millions)	Before-tax		After-tax		Before-tax		After-tax		Before-tax		After-tax
Transaction-related costs	$	126	$	92	$	166	$	147	$	66	$	57
Tax (benefit) - previously non-deductible costs		-		(59)		-		-		-		-
Transaction-related costs, net	$	126	$	33	$	166	$	147	$	66	$	57