Annual report pursuant to Section 13 and 15(d)

Income Taxes - Additional Information (Details)

v3.8.0.1
Income Taxes - Additional Information (Details) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Jan. 02, 2017
Income Tax Contingency [Line Items]      
Investment tax credit $ 11,900,000 $ 9,300,000  
Deferred tax asset, valuation allowance 5,386,000 663,000  
Valuation allowance, deferred tax asset, increase (decrease) 4,700,000    
Deferred tax assets, operating loss carryforwards, domestic   8,600,000  
Deferred tax assets, operating loss carryforwards, state and local   6,800,000  
Retained earnings $ 131,959,000 4,438,000  
Tax benefit realized upon settlement 50.00%    
Unrecognized tax benefits $ 1,500,000 1,500,000  
Unrecognized tax benefits, interest and penalties 400,000 300,000  
Unrecognized tax benefits, period increase (decrease) (1,100,000)    
U.S. Federal      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 699,600,000 571,300,000  
State      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 634,700,000    
California      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 387,200,000 348,200,000  
Other State      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 247,500,000 176,700,000  
California Enterprise Zone Credits.      
Income Tax Contingency [Line Items]      
Investment tax credit $ 0 $ 1,000,000  
Restatement Adjustment | ASU 2016-16      
Income Tax Contingency [Line Items]      
Prepaid tax assets, net     $ 378,500,000
Recognized deferred tax assets     378,200,000
Restatement Adjustment | ASU 2016-09      
Income Tax Contingency [Line Items]      
Deferred tax assets     3,300,000
Retained earnings     $ 3,300,000