Medical Costs Payable (Notes)

12 Months Ended

Dec. 31, 2017

Medical Costs Payable

Medical Costs Payable

The following table shows the components of the change in medical costs payable for the years ended December 31:

(in millions)	2017			2016			2015
Medical costs payable, beginning of period	$	16,391		$	14,330		$	12,040
Acquisitions	83			—			—
Reported medical costs:
Current year	130,726			117,258			104,195
Prior years	(690		)	(220		)	(320		)
Total reported medical costs	130,036			117,038			103,875
Medical payments:
Payments for current year	(113,811		)	(101,696		)	(90,630		)
Payments for prior years	(14,828		)	(13,281		)	(10,955		)
Total medical payments	(128,639		)	(114,977		)	(101,585		)
Medical costs payable, end of period	$	17,871		$	16,391		$	14,330

For the year ended December 31, 2017, medical cost reserve development was primarily driven by lower than expected health system utilization levels. For the years ended December 31, 2016 and 2015, no individual factors were significant.

Medical costs payable included IBNR of $12.3 billion and $11.6 billion at December 31, 2017 and 2016, respectively. Substantially all of the IBNR balance as of December 31, 2017 relates to the current year. The following is information about incurred and paid medical cost development as of December 31, 2017:

	Net Incurred Medical Costs
(in millions)	For the Years ended December 31,
Year	2016			2017
2016	$	117,258		$	116,622
2017				130,726
Total				$	247,348
	Net Cumulative Medical Payments
(in millions)	For the Years ended December 31,
Year	2016			2017
2016	$	(101,696	)	$	(116,187	)
2017				(113,811		)
Total				(229,998		)
Net remaining outstanding liabilities prior to 2016				521
Total medical costs payable				$	17,871