Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurement- Fair Value and Carrying Value of Long-term Debt (Details)

v3.8.0.1
Fair Value Measurement- Fair Value and Carrying Value of Long-term Debt (Details) - USD ($)
Sep. 30, 2017
Dec. 31, 2016
Fair Value Disclosures [Abstract]    
Long-term debt value, fair value $ 173,918,000 $ 145,746,000
Long-term debt value, carrying value 173,808,000 145,238,000
Assets, fair value disclosure, nonrecurring $ 0 $ 0