Income Taxes - Deferred Income Tax Assets and Liabilities (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Deferred tax assets:
Accrued liabilities and reserves	$ 16,254	$ 11,832
Revenue recognition	4,284	4,096
Tax credit and loss carryforwards	3,295	1,971
Fixed assets and intangibles	392	499
Unrealized investment	4,618	1,471
Stock compensation	1,718	2,807
Other assets	1,635	1,584
Gross deferred tax assets	32,196	24,260
Valuation allowance	(2,216)	(2,123)
Net deferred tax assets	29,980	22,137
Deferred tax liabilities:
Fixed assets and intangibles	(8,245)	(5,589)
Revenue recognition	(4,882)	(4,053)
Other liabilities	(3,645)	(4,088)
Total deferred tax liabilities	(16,772)	(13,730)
Net deferred tax assets	13,208	8,407
Deferred Income Taxes [Abstract]
Deferred tax assets - current	18,899	11,505
Deferred tax assets - noncurrent	934	1,072
Other current liabilities	(18)	(64)
Deferred tax liabilities - noncurrent	(6,607)	(4,106)
Net deferred tax assets	13,208	8,407
Valuation allowance	$ (2,216)	$ (2,123)