Leases - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018	Jan. 01, 2018
Operating Leased Assets [Line Items]
ROU asset	$ 42,847		$ 8,504	$ 10,100
Lease liability	$ 45,872			$ 12,300
Renewal term on lease	5 years
Columbia, Maryland
Operating Leased Assets [Line Items]
ROU asset		$ 32,300
Lease liability		$ 32,000
Remaining terms of leases		147 months
Obligations for operating lease	$ 72,200
Minimum
Operating Leased Assets [Line Items]
Remaining terms of leases	1 year
Option to terminate lease	2 years
Maximum
Operating Leased Assets [Line Items]
Remaining terms of leases	12 years
Option to terminate lease	5 years