Acquistions intangible (Details) (USD $)	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Percentage acquired	51.00%	49.00%
Purchase amount	$ 43,000,000	$ 43,000,000
Amortization of Acquired Intangible Assets	0
Acquired Indefinite-lived Intangible Assets [Line Items]	$ 3,000,000

The aggregate expense charged against earnings to allocate the cost of acquired intangible assets. As a noncash expense, this element is added back to net income when calculating cash provided by (used in) operations using the indirect method.

No definition available.

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