Share Based Compensation - Restricted Stock Awards (Details) - Restricted shares - $ / shares
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2019
Sep. 30, 2018
Avg wtd grant-date fair value      
Unvested at beginning of period   $ 13.17 $ 11.82
Granted   16.27 13.81
Vested   11.06 10.48
Forfeited   13.49  
Unvested at end of period $ 14.25 $ 14.25 $ 13.18
Units      
Unvested at beginning of period   2,997,856 1,293,107
Granted (in shares) 196,476 1,192,145 1,904,595
Vested (in shares) (3,660) (212,929) (209,765)
Forfeited (in shares)   (433,549)  
Unvested at end of period 3,543,523 3,543,523 2,987,937