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Unrecognized tax benefits (Details 7) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] |  |  |
Balance at beginning of year | $ 105,000 | $ 7,845,000 | $ 7,845,000
Settlements | 0 | (7,740,000) | 0
Lapse of statute of limitations | (105,000) | 0 | 0
Balance at end of year | 0 | 105,000 | 7,845,000
Unrecognized tax benefits highly certain deductibility | 0 | 0 |
Unrecognized tax benefits that would affect the effective tax rate |  | 119,000 |
Unrecognized tax benefits, interest and penalties |  | 14,000 |
Interest expense recognized in income tax expense | 122,000 | 387,000 | 107,000
Interest expense | 3,400,000 | 1,200,000 | 914,000
Interest income | 3,700,000 | 469,000 | $ 655,000
Accrued liability for payment of interest | $ 94,000 |  |
Amount of interest income accrued for an over payment of income taxes |  | $ 367,000 |

X
- Definition Amount of interest income accrued for an over payment of income taxes. + References No definition available. + Details
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- Definition Interest expense recognized in income tax expense. + References No definition available. + Details
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- Definition This element represents interest income recognized for an overpayment of income taxes computed by applying the applicable statutory rate of interest to the difference between a tax position recognized for financial reporting purposes and the amount previously taken or expected to be taken in a tax return of the entity. + References No definition available. + Details
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- Definition The amount of interest and penalties on unrecognized tax benefits that would affect the effective tax rate. + References No definition available. + Details
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- Definition The gross amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns where the likelihood of deductibility is highly certain. + References No definition available. + Details
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- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
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- Definition Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Unrecognized Tax Benefit -URI http://asc.fasb.org/extlink&oid=6527854 + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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- Definition Amount of interest expense accrued for an underpayment of income taxes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319 + Details
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- Definition Amount of interest expense for an underpayment of income taxes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319 + Details
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- Definition Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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- Definition The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 15A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319 + Details
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