Equity - Carrying Amounts and Classification of Variable Interest Entities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 71,684	$ 56,664
Accounts receivable	70,350	113,635
Other current assets	11,818	6,109
Total current assets	204,874	236,128
Goodwill	120,343	120,343	$ 120,343	$ 120,154
Other assets	4,139	5,647
Total Assets	366,667	422,968	$ 488,738
Current liabilities:
Accounts Payable and Accrued Liabilities	27,322	48,245
Other current liabilities	1,295	1,697
Total current liabilities	90,661	141,955
Long-term liabilities:
Long-term portion of Senior Credit Facility	100,000	123,000
Other long-term liabilities	30	217
Total liabilities	190,918	265,667
Variable Interest Entity, Primary Beneficiary
Current assets:
Cash and cash equivalents	71,442	56,598
Accounts receivable	70,350	113,635
Other current assets	55,575	64,476
Total current assets	197,367	234,709
Goodwill	120,343	120,343
Other assets	15,259	37,826
Total non-current assets	135,602	158,169
Total Assets	332,969	392,878
Current liabilities:
Accounts Payable and Accrued Liabilities	61,436	86,097
Other current liabilities	43,676	65,863
Total current liabilities	105,112	151,960
Long-term liabilities:
Long-term portion of Senior Credit Facility	100,000	123,000
Other long-term liabilities	256	712
Liabilities, Noncurrent, Total	100,256	123,712
Total liabilities	$ 205,368	$ 275,672