Consolidated Balance Sheets (Parenthetical) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Stockholders' equity:
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Shares Authorized	400,000,000	400,000,000
Common Stock, Shares Issued	123,352,185	123,352,185
Common Stock, Shares Outstanding	103,694,613	106,606,619
$25 Par Preferred Stock [Member]
Stockholders' equity:
Preferred Stock, Par Value	$ 25	$ 25
Preferred Stock, Dividend Rate	4.00%	4.00%
Preferred Stock, Shares Authorized	840,000	840,000
Preferred Stock, Shares Issued	649,736	649,736
Preferred Stock, Shares Outstanding	242,170	242,170