Litigation, Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Sep. 30, 2019	Dec. 31, 2020	Dec. 31, 2019
Loss Contingency [Abstract]
Estimated recoverable amount	$ 455,462		$ 455,564
Additional allowance for expected credit losses, net of tax	0		0
ASU 2016-13 [Member]
Loss Contingency [Abstract]
Allowance for credit losses, before tax	16,500			$ 15,000
Allowance for credit losses, net of tax	13,035			$ 11,850
Allowance For Doubtful Accounts Receivable Period Increase Decrease, Before Tax		$ 1,500
Additional allowance for expected credit losses, net of tax		$ 1,185
Charge incurred to operations, gross			30,500
Charge incurred to operations, net of tax			$ 24,095
Personnel Staffing Group d/b/a MVP Staffing [Member]
Loss Contingency [Abstract]
Per claim deductible amount	500
Damages sought	$ 0
Percentage of required collateral	110.00%
Deductible receivables	$ 24,068
Average monthly deductible invoices	778
Estimated recoverable amount	47,000
Personnel Staffing Group d/b/a MVP Staffing [Member] | Minimum [Member]
Loss Contingency [Abstract]
Loss fund	$ 4,000