Consolidated Statement of Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 8,015	$ 5,097
Other comprehensive income (loss), net of tax:
Change in market value of securities	7,113	(95)
Tax effect of change in market value of securities	(3,041)	38
Foreign currency translation adjustments	(657)	(94)
Other comprehensive income (loss)	3,415	(151)
Comprehensive income	$ 11,430	$ 4,946

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

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

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+ Details

- Definition

Amount after tax and reclassification adjustments, resulting from the process of expressing in the reporting currency of the reporting entity those amounts that are denominated or measured in a different currency, and from transactions whose terms are denominated in a currency other than the entity's functional currency, which is attributable to the parent entity.

+ References

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+ Details

- Definition

Net of tax amount of other comprehensive income (loss) attributable to the parent entity.

+ References

+ Details

- Definition

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

+ References

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+ Details

- Definition

Tax effect of unrealized holding gain (loss) before reclassification adjustments and transfers on available-for-sale securities.

+ References+ Details