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Components of net periodic benefit cost (Tables)

3 Months Ended

Mar. 31, 2016

Components of net periodic benefit cost [Abstract]

Schedule of net periodic benefit cost

	Pension Benefits
		Three months ended March 31,
		2016			2015
Service cost		$	1,270		$	1,704
Interest cost		3,480			3,388
Expected return on plan assets		(4,816		)	(5,494		)
Amortization of prior service costs		28			25
Amortization of net loss		1,043			620
Net periodic benefit cost		$	1,005		$	243

	Other Postretirement Benefits ("OPEB")
		Three months ended March 31,
		2016			2015
Service cost		$	330		$	562
Interest cost		1,456			1,591
Amortization of prior service cost		(695		)	(961		)
Amortization of net loss		876			865
Net periodic benefit cost		$	1,967		$	2,057

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- Definition

Components of net periodic benefit cost [Abstract]

+ References

No definition available.

+ Details

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- Definition

Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments.

+ 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 (h)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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