General - Allowance for Credit Losses on Premium Receivables (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Premiums Receivable, Allowance for Doubtful Accounts [Roll Forward]
Beginning balance	$ 1,445	$ 1,458
Provision during the period for expected credit losses	8,169	1,563
Write-off amounts during the period	(1,658)	(1,870)
Recoveries during the period of amounts previously written off	189	170
Ending balance	10,000	1,321
Cumulative Effect, Period Of Adoption, Adjustment [Member]
Premiums Receivable, Allowance for Doubtful Accounts [Roll Forward]
Beginning balance	1,855	0
Cumulative Effect, Period Of Adoption, Adjusted Balance [Member]
Premiums Receivable, Allowance for Doubtful Accounts [Roll Forward]
Beginning balance	$ 3,300	$ 1,458