Stockholders' Equity Common Stock (Details)	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 29, 2012
Common stock issued, Class A
Capital Stock Activity [Roll Forward]
Common stock issued, beginning balance (in shares)	2,600,000		2,600,000		2,600,000
Shares issued under equity compensation plans	0		0		0
Shares exchanged for common stock	0		0
Common stock issued, ending balance (in shares)	2,600,000		2,600,000		2,600,000
Common stock issued, Class B
Capital Stock Activity [Roll Forward]
Common stock issued, beginning balance (in shares)	167,200,000	[1]	164,200,000	[1]	162,700,000	[1]
Shares issued under equity compensation plans	1,300,000	[1]	2,700,000	[1]	1,500,000	[1]
Shares exchanged for common stock	1,400,000	[1]	300,000	[1]
Common stock issued, ending balance (in shares)	169,900,000	[1]	167,200,000	[1]	164,200,000	[1]
Exchangeable shares issued, Class A
Capital Stock Activity [Roll Forward]
Exchangeable stock issued, beginning balance (in shares)	2,900,000		2,900,000		2,900,000
Shares issued under equity compensation plans	0		0		0
Shares exchanged for common stock	0		0
Exchangeable stock issued, ending balance (in shares)	2,900,000		2,900,000		2,900,000
Exchangeable shares issued, Class B
Capital Stock Activity [Roll Forward]
Exchangeable stock issued, beginning balance (in shares)	19,000,000		19,300,000		19,300,000
Shares issued under equity compensation plans	0		0		0
Shares exchanged for common stock	(1,400,000)		(300,000)
Exchangeable stock issued, ending balance (in shares)	17,600,000		19,000,000		19,300,000

[1] During 2011, we repurchased Class B common shares which results in a lower number of outstanding shares compared to issued shares. See "Share Repurchase Program" below for further discussion. For all other classes, issued shares equal outstanding shares.