Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Dividend per share to common stockholders (in dollars per share)	$ 1.20	$ 1.20	$ 1.20
Cumulative Dividends
Dividend per share to common stockholders (in dollars per share)	1.20	1.20	1.20
Total Stockholders' Equity
Dividend per share to common stockholders (in dollars per share)	$ 1.20	$ 1.20	$ 1.20