Consolidated Condensed Statements of Equity (Parenthetical) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2017	Sep. 30, 2016
Equity, Class of Treasury Stock [Line Items]
Preferred stock - cash dividends declared per share (in dollars per share)		$ 4,650	$ 4,650
Common stock - cash dividends declared per share (in dollars per share)		$ 0.27	$ 0.21
Common stock repurchased under share repurchase program	[1]	$ 5,285	$ 96,801
Stock Repurchase Authorization
Equity, Class of Treasury Stock [Line Items]
Common stock repurchased under share repurchase program			$ 93,500

[1] 2016 includes $93.5 million repurchased under share repurchase programs.