Employee Benefit Plans ( Equity Incentive Plan and Stock Option Activity) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		6 Months Ended
	May 25, 2017	Jun. 30, 2017
Number of Shares
Balance at beginning of period (in shares)		2.4
Exercised (in shares)		(0.4)
Expired/canceled (in shares)		(0.7)
Balance at end of period (in shares)		1.3
Weighted Average Exercise Price per Share
Balance at beginning of period (in dollars per share)		$ 29.20
Exercised (in dollars per share)		16.63
Expired/canceled (in dollars per share)		30.83
Balance at end of period (in dollars per share)		$ 32.46
Weighted average remaining contractual term at end of period		1 year 2 months 12 days
Aggregate intrinsic value at end of period		$ 4.8
Vested or expected-to-vest options at end of period (in shares)		1.3
Vested or expected-to-vest options, weighted average exercise price at end of period (in dollars per share)		$ 32.46
Vested and expected-to-vest options, weighted average remaining contractual term at end of period		1 year 2 months 12 days
Vested or expected-to-vest options, aggregate intrinsic value at end of period		$ 4.8
Exercisable options at end of period (in shares)		1.2
Exercisable options, weighted average exercise price at end of period (in dollars per share)		$ 33.63
Exercisable options, weighted average remaining contractual term at end of period		10 months 24 days
Exercisable options, aggregate intrinsic value at end of period		$ 3.6
Equity incentive plan 2015 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (shares)	23.0
Share-Based Compensation Plans
Number of shares available for future issuance		35.5
Employee stock purchase plan 2008 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized (shares)	9.0
Share-Based Compensation Plans
Number of shares available for future issuance		12.4