Pension Plans, Retirement Benefits and Savings Plans (details) - Miscellaneous Fair Value Disclosures - item	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Qualified Domestic Pension Plan [Member] \| Equity securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	55.00%
Maximum investment in class of securities (as a percentage)	65.00%
Qualified Domestic Pension Plan [Member] \| Fixed income securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	20.00%
Maximum investment in class of securities (as a percentage)	40.00%
Qualified Domestic Pension Plan [Member] \| Private equity funds [Member]
Defined benefit plan disclosure
Number of private equity funds included in pension plan assets	2	2
Number of private equity funds included in pension plan assets focused on financial companies	1
Qualified Domestic Pension Plan [Member] \| Long-term growth [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	85.00%
Maximum investment in class of securities (as a percentage)	90.00%
Qualified Domestic Pension Plan [Member] \| Near-term benefit payments [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	10.00%
Maximum investment in class of securities (as a percentage)	15.00%
Postretirement Benefit Plans [Member] \| Fixed income securities [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	25.00%
Maximum investment in class of securities (as a percentage)	75.00%
Postretirement Benefit Plans [Member] \| Long-term growth [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	35.00%
Maximum investment in class of securities (as a percentage)	65.00%
Postretirement Benefit Plans [Member] \| Near-term benefit payments [Member]
Defined benefit plan disclosure
Minimum investment in class of securities (as a percentage)	35.00%
Maximum investment in class of securities (as a percentage)	60.00%

The number of investments in private equity funds.

No definition available.

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- Definition

The number of private equity funds focused on financial companies.

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ 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 (d)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e2446-114920

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