New accounting standards Balance sheet classification of deferred taxes (Details) $ in Thousands	Mar. 31, 2016 USD ($)
Accounting Standards Update 2015-17 [Member] | Restatement adjustment [Member] | Other current assets [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclass from current assets - deferred income taxes to deferred credits and other liabilities	$ 34,200