Income Taxes (Net Deferred Tax Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred Tax Assets [Abstract]
United States federal net operating loss carryforwards	$ 84,426	$ 66,547
Deferred expenses	1,591	2,552
Research and development tax credit carryforwards	24,442	22,979
Alternative minimum tax credit carryforward	3,626	3,626
Net unrealized loss on investments	97	97
Accrued loss on excess office facilities	959	0
Stock-based compensation	11,441	11,398
State net operating loss carryforwards	10,079	8,400
Foreign net operating loss carryforwards	30,657	34,210
Deferred revenue	82	401
Equipment, software, and leasehold improvements	4,263	3,252
Intangibles	12	19
Other	5,150	4,332
Gross deferred tax assets	176,825	157,813
Less valuation allowance	173,872	149,474
Gross deferred tax assets, net of valuation allowance	2,953	8,339
Deferred Tax Liabilities [Abstract]
Other intangible assets	(404)	(3,035)
Net unrealized gains and basis differences on investments	(78)	(4,226)
Other	(218)	(397)
Prepaid expenses	(1,384)	(1,360)
Gross deferred tax liabilities	(2,084)	(9,018)
Net deferred tax assets	$ 869
Net deferred tax liabilities		$ (679)