Stock Plans (Tables)

6 Months Ended

Jun. 30, 2017

Stock Plans [Abstract]

LTIP Target Performance Shares

	Number of
	Shares
	(in thousands)
Balance at January 1, 2017	190
LTIP target performance shares granted, net	165
LTIP target performance shares earned	(41)
LTIP target performance shares forfeited	(19)
Balance at June 30, 2017	295

Restricted Shares Outstanding

		Weighted
		Average
	Number of	Grant Date		Aggregate
	Shares	Fair Value		Fair Value
	(in thousands)	(per share)		(in millions)
Balance at January 1, 2017	549	$	78.00	$	28
Restricted stock granted	454	$	62.25	$	8
Restricted stock vested	(217)	$	79.80	$	4
Restricted stock forfeited	(64)	$	63.15
Balance at June 30, 2017	722	$	69.00	$	13