Benefit Plans - Assumed Health Care Cost Trend Rates (Details)	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014
Health care cost trend rate assumed for the next year:
Pre-age 65 (as a percent)	7.50%	6.70%
Post-age 65 (as a percent)	8.00%	9.00%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	4.75%	5.00%
Year that the rate reaches the ultimate trend rate	2026	2021

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan for plan participants more than 65 years of age.

No definition available.

+ Details

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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan for plan participants less than 65 years of age.

+ References

No definition available.

+ Details

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Namespace Prefix:	af_
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- References

No definition available.

+ Details

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- Definition

The ultimate trend rate for health care costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (l)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

+ Details

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

+ References

+ Details

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