Significant Accounting Policies (Details 2)	12 Months Ended
Dec. 31, 2012 item
Segment disclosure
Number of primary operating subsidiaries that are entity's segments	3
Restricted stock units \| Minimum
Stock-based employee compensation
Requisite service period	1 year
Restricted stock units \| Maximum
Stock-based employee compensation
Requisite service period	5 years

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration