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Stockholders' equity - Additional Information (Details) - $ / shares | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Equity [Abstract] |  |
Cash dividends declared per common share (in dollars per share) | $ 0.90 | $ 0.77
Cash dividends paid per common share (in dollars per share) | $ 0.90 | $ 0.77

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- Definition Aggregate dividends paid during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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- Definition Aggregate dividends declared during the period for each share of common stock outstanding. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
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- References No definition available. + Details
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