New accounting pronouncements (Policies)	6 Months Ended
Jun. 30, 2012
Accounting Policies [Abstract]
New accounting pronouncements	New accounting pronouncements On January 1, 2012, we adopted Accounting Standards Update (ASU) No. 2011-05, Presentation of Comprehensive Income. This standard eliminates the option to report other comprehensive income and its components in the statement of shareholders' equity. Also effective January 1, 2012, we adopted ASU No. 2011-12, Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05. This standard temporarily defers a provision included in ASU No. 2011-05 which requires that reclassification adjustments from other comprehensive income to net income be presented by income statement line item. Our presentation of comprehensive income in this quarterly report on Form 10-Q complies with these accounting standards. On January 1, 2012, we adopted ASU No. 2011-04, Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S GAAP and IFRSs. The new guidance changes some fair value measurement principles and disclosure requirements. The changes in fair value measurement principles relate primarily to financial assets and did not affect the fair value measurements presented in this report on Form 10-Q. The fair value disclosures required by the new standard are presented in Note 7: Fair value measurements.

New accounting pronouncements

On January 1, 2012, we adopted Accounting Standards Update (ASU) No. 2011-05, Presentation of Comprehensive Income. This standard eliminates the option to report other comprehensive income and its components in the statement of shareholders' equity. Also effective January 1, 2012, we adopted ASU No. 2011-12, Deferral of the Effective Date for Amendments to the Presentation of Reclassifications of Items Out of Accumulated Other Comprehensive Income in Accounting Standards Update No. 2011-05. This standard temporarily defers a provision included in ASU No. 2011-05 which requires that reclassification adjustments from other comprehensive income to net income be presented by income statement line item. Our presentation of comprehensive income in this quarterly report on Form 10-Q complies with these accounting standards.

On January 1, 2012, we adopted ASU No. 2011-04, Amendments to Achieve Common Fair Value Measurement and Disclosure Requirements in U.S GAAP and IFRSs. The new guidance changes some fair value measurement principles and disclosure requirements. The changes in fair value measurement principles relate primarily to financial assets and did not affect the fair value measurements presented in this report on Form 10-Q. The fair value disclosures required by the new standard are presented in Note 7: Fair value measurements.