Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Services	$ 259,678	$ 362,130	$ 587,420	$ 690,921	$ 1,415,803	$ 1,475,088	$ 1,513,779
United States
Disaggregation of Revenue [Line Items]
Services	210,342	284,659	474,903	547,676
Canada
Disaggregation of Revenue [Line Items]
Services	16,609	24,564	34,865	46,942
Other
Disaggregation of Revenue [Line Items]
Services	32,727	52,907	77,652	96,303
Food & Beverage
Disaggregation of Revenue [Line Items]
Services	46,811	73,305	104,396	139,969
Retail
Disaggregation of Revenue [Line Items]
Services	32,728	39,894	69,537	72,350
Consumer Products
Disaggregation of Revenue [Line Items]
Services	34,855	45,296	74,189	78,232
Communications
Disaggregation of Revenue [Line Items]
Services	16,172	47,793	38,014	87,490
Automotive
Disaggregation of Revenue [Line Items]
Services	13,020	18,541	38,212	36,732
Technology
Disaggregation of Revenue [Line Items]
Services	38,846	28,876	88,341	54,279
Healthcare
Disaggregation of Revenue [Line Items]
Services	23,112	25,954	46,843	49,161
Financials
Disaggregation of Revenue [Line Items]
Services	19,748	27,868	43,753	52,795
Transportation and Travel/Lodging
Disaggregation of Revenue [Line Items]
Services	9,053	27,050	25,552	44,085
Other
Disaggregation of Revenue [Line Items]
Services	$ 25,333	$ 27,553	$ 58,583	$ 75,828