Discontinued operations - Summary of discontinued operations (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012
Discontinued Operations and Disposal Groups [Abstract]
Revenue of QCC and AMP		$ 1,002
Loss from operations of QCC and AMP		(948)
Income tax benefit		301
Net loss from operations of QCC and AMP		(647)
Loss on disposal of QCC and AMP		(998)
Income tax benefit		318
Net loss on disposal of QCC and AMP		(680)
Loss from discontinued operations		$ (1,327)

Amount of gain (loss), before tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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Amount of gain (loss), after tax expense or benefit and not previously recognized, resulting from the sale of a business component.

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Pretax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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After tax income (loss) from operations of a business component (exclusive of any gain (loss) on disposal, or provision therefore) during the reporting period, until its disposal.

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Income tax expense or benefit attributable to Income or Loss from discontinued operations during the phase-out period.

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Amount of tax expense or benefit on gain (loss), not previously recognized, resulting from the sale of a business component.

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Amount of sales or other form of revenues attributable to the disposal group, including a component of the entity (discontinued operation), during the reporting period.

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Amount of income (loss) from a disposal group, net of income tax, reported as a separate component of income before extraordinary items after deduction or consideration of the amount allocable to noncontrolling interests. Includes, net of tax, income (loss) from operations during the phase-out period, gain (loss) on disposal, provision (or any reversals of earlier provisions) for loss on disposal, and adjustments of a prior period gain (loss) on disposal.

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