Commitments and Contingencies (Details) - USD ($)		3 Months Ended	9 Months Ended	12 Months Ended
		Sep. 30, 2019	Sep. 30, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
Contractual Commitments, Commitment [Line Items]
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability			$ 100,000
Operating Lease, Payments			19,103
Lease Cost		$ 5,748,000	17,690,000
Short-term lease cost		23,000	113,000
Variable lease cost		388,000	834,000
Sublease income		(232,000)	(739,000)
Total lease costs		$ 5,927,000	$ 17,898,000
Weighted average remaining lease term - operating leases (in Years)		5 years 6 months 7 days	5 years 6 months 7 days
Weighted average discount rate -operating leases		4.14%	4.14%
Future minimum annual lease and service payments
Total Lease Liability		$ 100,934,000	$ 100,934,000	$ 0			$ 110,505,000
Sublease income related to operating leases				1,400,000	$ 1,100,000	$ 2,200,000
RCG Longview Partners II, LLC | Clawback Obligation
Future minimum annual lease and service payments
Contractual obligation		6,500,000	6,500,000	6,500,000
Equipment Leases
Contractual Commitments, Commitment [Line Items]
Contractual Obligation, Due in Next Fiscal Year				2,434,000
Contractual Obligation, Due in Second Year				1,492,000
Contractual Obligation, Due in Third Year				1,382,000
Contractual Obligation, Due in Fourth Year				1,123,000
Contractual Obligation, Due in Fifth Year				374,000
Contractual Obligation, Due after Fifth Year				0
Contractual Obligation				6,805,000
Future minimum annual lease and service payments
2019	[1]	94,000	94,000
2020	[1]	364,000	364,000
2021	[1]	177,000	177,000
2022	[1]	61,000	61,000
2023	[1]	0	0
Thereafter	[1]	0	0
Future minimum annual lease and service payments	[1]	696,000	696,000
Less discount		114,000	114,000
Total Lease Liability		582,000	582,000
Service Payments
Contractual Commitments, Commitment [Line Items]
Contractual Obligation, Due in Next Fiscal Year		6,691,000	6,691,000	21,758,000
Contractual Obligation, Due in Second Year		15,210,000	15,210,000	7,514,000
Contractual Obligation, Due in Third Year		8,483,000	8,483,000	1,877,000
Contractual Obligation, Due in Fourth Year		5,971,000	5,971,000	1,372,000
Contractual Obligation, Due in Fifth Year		3,573,000	3,573,000	735,000
Contractual Obligation, Due after Fifth Year		6,331,000	6,331,000	735,000
Contractual Obligation		46,259,000	46,259,000	33,991,000
Facility Leases
Contractual Commitments, Commitment [Line Items]
Contractual Obligation, Due in Next Fiscal Year				24,584,000
Contractual Obligation, Due in Second Year				22,608,000
Contractual Obligation, Due in Third Year				22,321,000
Contractual Obligation, Due in Fourth Year				19,166,000
Contractual Obligation, Due in Fifth Year				16,204,000
Contractual Obligation, Due after Fifth Year				21,478,000
Contractual Obligation				$ 126,361,000
Future minimum annual lease and service payments
2019	[2]	4,530,000	4,530,000
2020	[2]	24,350,000	24,350,000
2021	[2]	24,049,000	24,049,000
2022	[2]	20,586,000	20,586,000
2023	[2]	17,416,000	17,416,000
Thereafter	[2]	25,958,000	25,958,000
Future minimum annual lease and service payments	[2]	116,889,000	116,889,000
Less discount		16,424,000	16,424,000
Total Lease Liability		$ 100,352,000	$ 100,352,000

[1] In the third quarter of 2019, the Company recognized operating ROU assets and leases liabilities of $0.1 million for equipment leases.

[2] The Company has entered into various agreements to sublease certain of its premises.