Income Taxes (Narrative) (Details)	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Income Tax Disclosure [Abstract]
Uncertain income tax percentage of likelihood	0.5
Unrecognized tax benefits	$ 0
Accrual for interest or penalties	0	$ 0
Recognized interest and penalties	0	$ 0	$ 0
Domestic Tax Authority [Member]
Income Tax Disclosure [Line Items]
Income tax net operating loss carryforwards	447,342,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Income Tax Disclosure [Line Items]
California research and development tax credit carryforwards	19,450,000
State and Local Jurisdiction [Member]
Income Tax Disclosure [Line Items]
Income tax net operating loss carryforwards	350,778,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Income Tax Disclosure [Line Items]
California research and development tax credit carryforwards	$ 11,734,000