Income Taxes (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Components of income before income taxes
U.S income	$ 146,420	$ 106,184	$ 64,359
Foreign	1,458	(2,041)	(2,863)
Income before income taxes	$ 147,878	$ 104,143	$ 61,496

The portion of earnings (loss) from continuing operations before income taxes that is attributable to foreign operations, which is defined as income (loss) generated from operations located outside the entity's country of domicile.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph h

-Subparagraph 1(i)

-Article 4

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration