For defined benefit pension plans, the actuarial present value of benefits (whether vested or nonvested) attributed by the pension benefit formula to employee service rendered before a specified date and based on employee service and compensation (if applicable) before that date. The accumulated benefit obligation differs from the projected benefit obligation in that it includes no assumption about future compensation levels. For plans with flat-benefit or nonpay-related pension benefit formulas, the accumulated benefit obligation and the projected benefit obligation are the same.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Accumulated Benefit Obligation
-URI http://asc.fasb.org/extlink&oid=6503844

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 30
-Section 35
-Paragraph 50
-URI http://asc.fasb.org/extlink&oid=29635418&loc=d3e12355-114930

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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Employee Benefit Plans (Fair Value of the Company’s Qualified Pension Plan Assets by Category) (Details) - Pension plans - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 43,603	$ 48,656	$ 49,873
Accumulated benefit obligation	45,500	48,200
Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	5,614	6,356
Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	36,954	41,351
Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	1,035	949
Quoted prices in active markets for identical assets (Level 1)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	1,035	949
Quoted prices in active markets for identical assets (Level 1) \| Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Quoted prices in active markets for identical assets (Level 1) \| Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Quoted prices in active markets for identical assets (Level 1) \| Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	1,035	949
Significant observable inputs (Level 2)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	42,568	47,707
Significant observable inputs (Level 2) \| Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	5,614	6,356
Significant observable inputs (Level 2) \| Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	36,954	41,351
Significant observable inputs (Level 2) \| Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3)
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) \| Equity Securities
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) \| Fixed Income Funds
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	0	0
Significant unobservable inputs (Level 3) \| Cash and Cash Equivalents
Defined Benefit Plans and Other Postretirement Benefit Plans
Fair value of qualified plan assets	$ 0	$ 0