Annual report pursuant to Section 13 and 15(d)

Business and summary of significant accounting policies - Income taxes and advertising expense (Details)

v3.7.0.1
Business and summary of significant accounting policies - Income taxes and advertising expense (Details) - USD ($)
1 Months Ended 12 Months Ended
Jun. 30, 2015
Dec. 31, 2016
Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]      
Decrease in valuation allowance $ 7,700,000 $ 12,000,000  
Unrecognized tax benefits   0 $ 0
Advertising expense   $ 3,200,000 $ 2,400,000