Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net earnings	$ 8,838	$ 2,178
Unrealized gain on short-term investments	19	50
Changes in pension plan assets and benefit obligations	(4)	(4)
Total comprehensive income	$ 8,853	$ 2,224

The change in equity [net assets] of a business enterprise during a period from transactions and other events and circumstances from non-owner sources which are attributable to the reporting entity. It includes all changes in equity during a period except those resulting from investments by owners and distributions to owners, but excludes any and all transactions which are directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent.

+ References+ Details

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

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

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

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Reference 5: http://www.xbrl.org/2003/role/presentationRef

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Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Glossary Net Income

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Reference 9: http://www.xbrl.org/2003/role/presentationRef

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Reference 10: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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Reference 11: http://www.xbrl.org/2003/role/presentationRef

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Reference 12: http://www.xbrl.org/2003/role/presentationRef

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Reference 13: http://www.xbrl.org/2003/role/presentationRef

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Reference 14: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

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Reference 15: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

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Reference 16: http://www.xbrl.org/2003/role/presentationRef

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+ Details

- Definition

Net of tax amount of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

+ References

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

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

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

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-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669646-108580

+ Details