Liability for Unpaid Claims - Summary of Liability for Unpaid Health Claims (Details) - Health Insurance [Member] - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Activity in the Liability for Unpaid Health Claims
Balance at beginning of period	$ 146,865	$ 143,128
Incurred related to:
Current year	411,662	393,747
Prior years	(3,795)	(10,745)
Total incurred	407,867	383,002
Paid related to:
Current year	293,800	279,563
Prior years	113,109	103,010
Total paid	406,909	382,573
Balance at end of period	$ 147,823	$ 143,557