Segment Information (Tables)

12 Months Ended

Dec. 31, 2012

Segment Reporting Information, Additional Information [Abstract]

Segment information

Presented below are segment data for the three years ended December 31, 2012, 2011 and 2010.

2012

	Western Region Operations		Government Contracts		Divested Operations and Services			Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	10,459.1	$	689.1	$	—		$	—		$	11,148.2
Intersegment revenues	11.0		—		—			(11.0		)	—
Net investment income	82.4		—		—			—			82.4
Administrative services fees and other income	18.0		—		—			—			18.0
Divested operations and services revenue	—		—		40.5			—			40.5
Interest expense	33.2		—		—			—			33.2
Depreciation and amortization	31.1		—		—			—			31.1
Share-based compensation expense	24.1		4.2		0.6			—			28.9
Segment pretax income (loss)	29.2		89.9		(45.4		)	(42.0		)	31.7

2011

	Western Region Operations		Government Contracts		Divested Operations and Services			Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	9,876.3	$	1,416.6	$	2.4		$	—		$	11,295.3
Intersegment revenues	11.8		—		—			(11.8		)	—
Net investment income	74.1		—		0.1			—			74.2
Administrative services fees and other income	11.5		—		—			—			11.5
Divested operations and services revenue	—		—		34.5			—			34.5
Interest expense	31.9		—		0.2			—			32.1
Depreciation and amortization	31.2		—		—			—			31.2
Share-based compensation expense	22.6		4.0		1.0			—			27.6
Segment pretax income (loss)	264.9		185.2		(88.9		)	(199.4		)	161.8

 2010

	Western Region Operations		Government Contracts		Divested Operations and Services			Corporate/Other/ Eliminations			Total
	(Dollars in millions)
Revenues from external sources	$	9,421.3	$	3,344.5	$	71.2		$	—		$	12,837.0
Intersegment revenues	54.2		0.1		—			(54.3		)	—
Net investment income	70.3		—		0.9			—			71.2
Administrative services fees and other income	26.6		—		—			(5.5		)	21.1
Divested operations and services revenue	—		—		186.2			—			186.2
Interest expense	34.9		—		—			—			34.9
Depreciation and amortization	33.2		—		0.2			—			33.4
Share-based compensation expense	26.0		4.1		3.0			—			33.1
Segment pretax income (loss)	210.1		178.8		(84.6		)	(23.7		)	280.6

Premium revenue by line of business

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

	Year Ended December 31,
	2012		2011		2010
	(Dollars in millions)
Commercial premium revenue	$	5,705.5	$	5,945.9	5,663.9
Medicare premium revenue	2,790.5		2,437.1		2,524.1
Medicaid premium revenue	1,963.1		1,493.3		1,233.3
Total Western Region Operations health plan services premiums	10,459.1		9,876.3		9,421.3
Total Divested Operations and Services health plan services premiums	—		2.4		71.2
Total health plan services premiums	$	10,459.1	$	9,878.7	$	9,492.5