Income Taxes (Details 1) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Components of income before income taxes
U.S. income	$ 119,325	$ 146,420	$ 106,184
Foreign	808	1,458	(2,041)
Income before income taxes	$ 120,133	$ 147,878	$ 104,143

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

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.(h)(1)(i))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

Reference 2: 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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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration