Summary of Significant Accounting Policies - Long-Lived Assets (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and intangible assets
Long-lived intangible impairment		$ 0	$ 0	$ 32,300,000
Total intangible assets		13,320,000	13,320,000
Less accumulated amortization		(12,091,000)	(11,113,000)
Net intangible assets		1,229,000	2,207,000
Amortization expense		1,000,000	1,400,000	$ 5,100,000
Estimated amortization expense
2020		800,000
2021		500,000
Customer relationships
Goodwill and intangible assets
Total intangible assets		$ 5,376,000	5,376,000
Customer relationships | Minimum
Goodwill and intangible assets
Estimated useful lives		1 year
Customer relationships | Maximum
Goodwill and intangible assets
Estimated useful lives		8 years
Acquired contracts
Goodwill and intangible assets
Total intangible assets		$ 4,384,000	4,384,000
Acquired contracts | Minimum
Goodwill and intangible assets
Estimated useful lives		1 year
Acquired contracts | Maximum
Goodwill and intangible assets
Estimated useful lives		10 years
Trademark and trade names
Goodwill and intangible assets
Total intangible assets		$ 2,700,000	2,700,000
Trademark and trade names | Minimum
Goodwill and intangible assets
Estimated useful lives		2 years
Trademark and trade names | Maximum
Goodwill and intangible assets
Estimated useful lives		10 years
Non-compete agreements
Goodwill and intangible assets
Estimated useful lives		3 years
Total intangible assets		$ 860,000	$ 860,000
Facility Closing
Goodwill and intangible assets
Long-lived intangible impairment	$ 20,400,000
CEC
Goodwill and intangible assets
Long-lived intangible impairment	$ 32,300,000