Income Taxes (Narrative) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Income tax expense (benefit)	$ 22,495,000	$ 16,743,000	$ (76,316,000)
Decrease in valuation allowance	(200,000)	1,300,000	116,900,000
Unrecognized tax benefits	6,029,000	4,756,000	4,139,000	$ 3,527,000
Unrecognized tax benefits, accrued interest	0	0	0
Unrecognized tax benefits, accrued penalties	$ 0	$ 0	$ 0
Document Period End Date	Dec. 31, 2019
Federal
Income Taxes [Line Items]
Net operating loss carryforwards	$ 7,700,000
California State
Income Taxes [Line Items]
Net operating loss carryforwards	75,200,000
Research and development tax credits	7,500,000
Other States
Income Taxes [Line Items]
Net operating loss carryforwards	9,700,000
Research and development tax credit | Federal
Income Taxes [Line Items]
Research and development tax credits	10,400,000
Orphan drug tax credit | Federal
Income Taxes [Line Items]
Research and development tax credits	$ 14,600,000