Stockholders' Equity (Dividends Declared on Common Stock) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 15, 2013	Mar. 23, 2013	Jun. 16, 2012	Mar. 24, 2012	Jun. 15, 2013	Jun. 16, 2012
Dividends Payable [Line Items]
Date Declared	May 14, 2013	Mar. 14, 2013	May 15, 2012	Mar. 16, 2012
Per-Share Amounts	$ 0.2	$ 0.175	$ 0.175	$ 0.145
Total	$ 48.2	$ 42.2	$ 41.9	$ 36.3	$ 90.4	$ 78.2
Dividends Declared On Common Stock Member
Dividends Payable [Line Items]
Record Date	Jun. 20, 2013	Mar. 25, 2013	Jun. 21, 2012	Mar. 29, 2012

Equity impact of aggregate cash, stock, and paid-in-kind dividends declared for all securities (common shares, preferred shares, etc.) during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.3-04)

-URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 405

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 01-6

-Paragraph 14

-Subparagraph l

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_Dividends
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration