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Income taxes, Income Tax Contingency (Details) (USD $)
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12 Months Ended |
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Dec. 31, 2013
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Dec. 31, 2012
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Dec. 31, 2011
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| Income Tax Contingency [Line Items] |
|
|
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| Accrued interest and penalties related to unrecognized tax benefits |
$ 15,000 |
$ 25,000 |
|
| Unrecognized tax benefits, current |
132,000 |
153,000 |
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| Unrecognized tax benefits, noncurrent |
991,000 |
863,000 |
|
| Estimated unrecognized tax benefits expected to be reversed within next twelve months |
152,000 |
75,000 |
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| Gross unrecognized tax benefits activity [Roll Forward] |
|
|
|
| Gross unrecognized tax benefits, beginning balance |
1,016,000 |
1,056,000 |
950,000 |
| Increases for tax positions for prior years |
165,000 |
25,000 |
167,000 |
| Decreases for tax positions for prior years |
0 |
(65,000) |
(61,000) |
| Increases for tax positions for current year |
15,000 |
0 |
0 |
| Settlements |
0 |
0 |
0 |
| Lapse of statute of limitations |
(75,000) |
0 |
0 |
| Gross unrecognized tax benefits, ending balance |
$ 1,121,000 |
$ 1,016,000 |
$ 1,056,000 |
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U.S. Federal Tax Authority [Member] | Minimum [Member]
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| Gross unrecognized tax benefits activity [Roll Forward] |
|
|
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| Open tax year |
2010 |
|
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| Federal income tax year selected for audit |
2008 |
|
|
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U.S. Federal Tax Authority [Member] | Maximum [Member]
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|
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| Gross unrecognized tax benefits activity [Roll Forward] |
|
|
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| Open tax year |
2012 |
|
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| Federal income tax year selected for audit |
2010 |
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|
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United Kingdom Tax Authority [Member] | Minimum [Member]
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|
|
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| Gross unrecognized tax benefits activity [Roll Forward] |
|
|
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| Open tax year |
2006 |
|
|
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United Kingdom Tax Authority [Member] | Maximum [Member]
|
|
|
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| Gross unrecognized tax benefits activity [Roll Forward] |
|
|
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| Open tax year |
2013 |
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