Liability for Unpaid Claims - Summary of Liability for Unpaid Health Claims (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Activity in the Liability for Unpaid Health Claims
Balance at beginning of period	$ 154,528	$ 146,865
Incurred related to:
Total incurred	611,117	552,630	$ 512,480
Paid related to:
Total paid	601,837	544,967	508,743
Balance at end of period	163,808	154,528	146,865
Health premium
Activity in the Liability for Unpaid Health Claims
Balance at beginning of period	154,528	146,865	143,128
Incurred related to:
Current year	612,305	555,647	520,528
Prior years	(1,188)	(3,017)	(8,048)
Paid related to:
Current year	470,426	424,633	394,506
Prior year	$ 131,411	120,334	114,237
Balance at end of period		$ 154,528	$ 146,865