Stock Plans (Tables)

3 Months Ended

Mar. 31, 2018

Stock Plans [Abstract]

LTIP Target Performance Shares

	Number of
	Shares
	(in thousands)
Balance at January 1, 2018	306
LTIP target performance shares granted, net	284
LTIP target performance shares earned	(18)
LTIP target performance shares forfeited	(8)
Balance at March 31, 2018	564

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, 2018	633	$	58.63	$	4
Restricted stock granted	1,897	$	8.23	$	14
Restricted stock vested	(219)	$	66.41	$	(2)
Restricted stock forfeited	(39)	$	57.87
Balance at March 31, 2018	2,272	$	15.80	$	17