Commitments, Guarantees and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014
Loss Contingencies [Line Items]
Purchase obligations in 2015	94,000,000
Purchase obligations in 2016	45,000,000
Purchase obligations in 2017	20,000,000
Purchase obligations in 2018	16,000,000
Purchase obligations thereafter	0
New Tricare South Region Contract
Loss Contingencies [Line Items]
Contract term, years	5 years
Puerto Rico Health Insurance Administration Contracts East Southeast And Southwest Regions
Loss Contingencies [Line Items]
Contract term, years	3 years
Medicare
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	72.00%
Military Services
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	1.00%
Medicaid
Loss Contingencies [Line Items]
Percentage of premiums and services revenue	2.00%

Contract term, years.

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- Definition

Percentage Of Total Premium And Services Revenues

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the next fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 440

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6394976&loc=d3e25336-109308

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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- Definition

Amount of the fixed and determinable portion of the unrecorded unconditional purchase obligation maturing after the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

+ References

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