Income taxes: (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income taxes:
Federal income tax at statutory rates (as a percent)	35.00%	35.00%	35.00%	35.00%
Components of (loss) income before income taxes
Domestic	$ 6,078	$ 7,578	$ 903	$ 16,014
Foreign	(4,543)	(6,791)	(89)	(13,486)
Income before income taxes	$ 1,535	$ 787	$ 814	$ 2,528

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations.

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This element represents the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, and noncontrolling interest.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile.

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