Aggregate dividends paid during the period for each share of common stock outstanding.

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

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount remaining of a stock repurchase plan authorized.

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Stockholders' equity (Details Textual) - USD ($) $ / shares in Units, $ in Billions	1 Months Ended				3 Months Ended		6 Months Ended
	Jul. 29, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Subsequent Event [Line Items]
Common stock, dividends declared per share (in usd per share)			$ 1.00	$ 1.00
Amount available for stock repurchases under a board approved stock repurchase plan		$ 3.6			$ 3.6		$ 3.6
Dividends paid per share (in usd per share)		$ 1.00	$ 1.00		$ 1.00	$ 0.79	$ 2.0	$ 1.58
Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock, dividends declared per share (in usd per share)	$ 1.00