Quarterly report pursuant to Section 13 or 15(d)

Stockholders' Equity and Stock Based Compensation - Nonvested (Details)

v3.5.0.2
Stockholders' Equity and Stock Based Compensation - Nonvested (Details) - Restricted stock - USD ($)
$ / shares in Units, $ in Millions
 9 Months Ended 12 Months Ended
Sep. 30, 2016
Sep. 30, 2015
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Shares            
Nonvested shares at the beginning of the period 123,329          
Granted (in shares) 171,252   44,000 98,689 56,500 92,000
Vested (in shares) (79,718)          
Forfeited (in shares) (6,867)   (4,465) (34,487) (775) (3,525)
Nonvested shares at the end of the period 207,996   123,329      
Weighted Average Grant Date Fair Value            
Nonvested shares at the beginning of period (in dollars per share) $ 16.34          
Granted (in dollars per share) 17.03          
Vested (in dollars per share) 14.57          
Forfeited (in dollars per share) 16.12          
Nonvested shares at the end of period (in dollars per share) $ 15.44   $ 16.34      
Unrecognized compensation cost (in dollars) $ 3.2          
Weighted average period for recognition of unrecognized compensation cost 3 years 4 months 24 days          
General and Administrative Expense            
Weighted Average Grant Date Fair Value            
Share-based compensation cost (in dollars) $ 1.2 $ 0.8