Liability for Unpaid Health Claims - Summary of Liability for Unpaid Health Claims (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Activity in the Liability for Unpaid Health Claims
Balance at beginning of year	$ 128,265	$ 116,559	$ 124,999
Incurred related to:
Current year	502,009	453,014	453,538
Prior years	(7,845)	804	5,279
Total incurred	494,164	453,818	458,817
Paid related to:
Current year	379,037	343,648	354,358
Prior years	106,272	98,464	112,899
Total paid	485,309	442,112	467,257
Balance at end of year	$ 137,120	$ 128,265	$ 116,559