Consolidated Statement of Changes in Equity (Parenthetical) (USD $)	1 Months Ended		3 Months Ended			12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Consolidated Statement of Changes in Equity
Dividends that have been declared but not yet paid (in dollars per share)	$ 1.025	$ 0.855
Dividends declared in current period (in dollars per share)			$ 0.855	$ 0.855	$ 0.855	$ 3.59	$ 3.395	$ 2.36