Segment Information (Tables)

12 Months Ended

Dec. 31, 2015

Segment Reporting Information, Additional Information [Abstract]

Segment information

Presented below are segment data for the three years ended December 31, 2015, 2014 and 2013.

2015

	Western Region Operations		Government Contracts		Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	15,553.3	$	628.5	$	—		$	16,181.8
Intersegment revenues	13.8		—		(13.8		)	—
Net investment income	55.5		—		—			55.5
Administrative services fees and other income	6.3		—		—			6.3
Interest expense	33.3		—		—			33.3
Depreciation and amortization	22.0		—		0.5			22.5
Share-based compensation expense	26.5		3.0		—			29.5
Segment pretax income (loss)	547.4		25.4		(118.2		)	454.6
Segment net income (loss)	244.3		14.2		(72.8		)	$	185.7

2014

	Western Region Operations			Government Contracts		Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	13,361.2		$	604.0	$	—		$	13,965.2
Intersegment revenues	12.4			—		(12.4		)	—
Net investment income	45.2			—		—			45.2
Administrative services fees and other income	(1.7		)	—		—			(1.7		)
Interest expense	31.4			—		—			31.4
Depreciation and amortization	29.7			—		0.1			29.8
Share-based compensation expense	25.0			3.3		—			28.3
Segment pretax income (loss)	315.6			69.5		(185.3		)	199.8
Segment net income (loss)	146.2			41.3		(41.9		)	$	145.6

 2013

	Western Region Operations		Government Contracts		Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	10,377.1	$	572.3	$	—		$	10,949.4
Intersegment revenues	11.1		—		(11.1		)	—
Net investment income	69.6		—		—			69.6
Administrative services fees and other income	34.8		—		—			34.8
Interest expense	32.6		—		—			32.6
Depreciation and amortization	38.6		—		—			38.6
Share-based compensation expense	26.1		3.8		—			29.9
Segment pretax income (loss)	207.5		74.5		(12.0		)	270.0
Segment net income (loss)	133.9		43.5		(7.3		)	170.1

Premium revenue by line of business

Our health plan services premium revenue by line of business is as follows:

	Year Ended December 31,
	2015		2014		2013
	(Dollars in millions)
Commercial premium revenue	$	5,530.5	$	5,443.1	$	5,175.4
Medicare premium revenue	3,076.3		3,044.3		2,771.4
Medicaid premium revenue	6,429.6		4,755.9		2,430.3
Dual Eligibles premium revenue	516.9		117.9		—
Total health plan services premiums	$	15,553.3	$	13,361.2	$	10,377.1