Allowance for Expected Credit Losses Balances of Premiums Receivable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable, after Allowance for Credit Loss [Abstract]
Accounts receivable, net of allowance for expected credit losses	$ 189,671	$ 193,369
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance	578
Current period change for expected credit losses	1,576
Writeoffs of uncollectable accounts receivable	(1,820)
Balance	$ 334