Organization and Summary of Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Change in Contract with Customer, Asset [Roll Forward]
Contract assets	$ 5,984	$ 0
Contract assets, change	$ 5,984
Contract assets, percent change	0.00%
Change in Contract with Customer, Liability [Roll Forward]
Contract liabilities - current	$ 2,394	3,038	$ 3,279
Contract liabilities - current, change	$ (644)
Contract liabilities - current, percent change	(21.00%)
Contract liabilities - non-current	$ 1,851	$ 1,711	$ 1,883
Contract liabilities - non-current, change	$ 140
Contract liabilities - non-current, percent change	8.00%