Significant Accounting Principles and Policies - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Product Information [Line Items]
Impairment of long-lived assets	$ 0	$ 0	$ 0
Impairment of equity method investments	$ 0	$ 0	$ 0
U.S. Government Agencies | Accounts Receivable | Customer Concentration Risk
Product Information [Line Items]
Concentration risk (as a percent)	91.40%	96.00%
U.S. Government Agencies | Revenue Benchmark | Customer Concentration Risk
Product Information [Line Items]
Concentration risk (as a percent)	90.00%	93.00%
Minimum
Product Information [Line Items]
Customer account due period (in days)	30 days
Minimum | Machinery and equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	4 years
Minimum | Computer and equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	3 years
Minimum | Transportation equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	4 years
Minimum | Furniture and fixtures
Product Information [Line Items]
Useful life of property and equipment (in years)	5 years
Minimum | Leasehold improvements
Product Information [Line Items]
Useful life of property and equipment (in years)	3 years
Maximum
Product Information [Line Items]
Customer account due period (in days)	45 days
Maximum | Machinery and equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	20 years
Maximum | Computer and equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	7 years
Maximum | Transportation equipment
Product Information [Line Items]
Useful life of property and equipment (in years)	11 years
Maximum | Furniture and fixtures
Product Information [Line Items]
Useful life of property and equipment (in years)	12 years
Maximum | Leasehold improvements
Product Information [Line Items]
Useful life of property and equipment (in years)	16 years