Stock-based Compensation - Options Granted and Weighted Average Grant Date Fair Value of Options Granted (Details) - $ / shares	3 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Weighted-average grant date fair value of the options granted (in dollars per share)	$ 3.57
Options granted (in shares)	0	189,856	479,375