CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	490,000,000	490,000,000
Common stock, shares outstanding (in shares)	77,595,240	66,454,375
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred Stock, Dividend Rate, Percentage	5.875%	5.875%
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred stock, shares authorized (in shares)	10,000,000	10,000,000
Preferred stock, shares outstanding (in shares)	3,600,000	3,600,000