Cash and Marketable Securities - Textual (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2013	Dec. 31, 2012
Cash and Marketable Securities (Textual) [Abstract]
Restricted marketable securities included in other long-term assets				$ 42.9	$ 39.4
Impairment charges related to restricted marketable securities	$ 0	$ 0	$ 0

Total debt and equity financial instruments including: (1) securities held-to-maturity, (2) trading securities, and (3) securities available-for-sale which are intended to be held for greater than one year or the normal operating cycle, whichever is longer and that are pledged to one or more secured parties who have the right to buy, sell, or re-pledge the collateral.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.4-08.(b))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.12)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 6

-Article 9

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph b

-Article 4

Name:	us-gaap_MarketableSecuritiesRestrictedNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant