Preferred Stock - Certain Terms of the Preferred Stock (Details)	6 Months Ended
	Jun. 30, 2017 $ / shares shares
Series B Preferred
Class of Stock [Line Items]
Shares at $0.01 Par Value at issuance (in shares) | shares	155,000
Par value (in dollars per share) | $ / shares	$ 0.01
Shares outstanding (in shares) | shares	155,000
Price / Share | $ / shares	$ 1,000
Dividend Rate	16.50%
Redemption Term	8 years
Additional rate upon certain triggering events	3.00%
Series C Preferred
Class of Stock [Line Items]
Shares at $0.01 Par Value at issuance (in shares) | shares	55,000
Par value (in dollars per share) | $ / shares	$ 0.01
Shares outstanding (in shares) | shares	55,000
Price / Share | $ / shares	$ 1,000
Dividend Rate	16.50%
Redemption Term	8 years
Additional rate upon certain triggering events	3.00%
Redemption rights (as a percent)	65.00%
Series D Preferred
Class of Stock [Line Items]
Shares at $0.01 Par Value at issuance (in shares) | shares	100
Par value (in dollars per share) | $ / shares	$ 0.01
Shares outstanding (in shares) | shares	100
Price / Share | $ / shares	$ 1.00
Dividend Rate	14.75%
Redemption Term	8 years
Series E Preferred
Class of Stock [Line Items]
Shares at $0.01 Par Value at issuance (in shares) | shares	90,000
Par value (in dollars per share) | $ / shares	$ 0.01
Shares outstanding (in shares) | shares	90,000
Price / Share | $ / shares	$ 1,000
Dividend Rate	14.75%
Redemption Term	6 years
Additional rate	8.50%
Additional rate upon certain triggering events	3.00%
Series F Preferred
Class of Stock [Line Items]
Shares at $0.01 Par Value at issuance (in shares) | shares	240,500
Par value (in dollars per share) | $ / shares	$ 0.01
Shares outstanding (in shares) | shares	240,500
Price / Share | $ / shares	$ 1,000
Dividend Rate	7.25%
Redemption Term	6 years
Additional rate upon certain triggering events	3.00%
LIBOR | Series B Preferred
Class of Stock [Line Items]
Basis spread on variable rate	3.00%
LIBOR | Series C Preferred
Class of Stock [Line Items]
Basis spread on variable rate	3.00%
LIBOR | Series E Preferred
Class of Stock [Line Items]
Basis spread on variable rate	5.25%
LIBOR | Series F Preferred
Class of Stock [Line Items]
Basis spread on variable rate	6.25%
Minimum | Series B Preferred
Class of Stock [Line Items]
Additional rate	4.75%
Minimum | Series C Preferred
Class of Stock [Line Items]
Additional rate	4.75%
Maximum | Series B Preferred
Class of Stock [Line Items]
Additional rate	12.50%
Maximum | Series C Preferred
Class of Stock [Line Items]
Additional rate	12.50%
0-12 months | Series E Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	106.50%
0-12 months | Series F Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	106.50%
12-24 months | Series B Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	105.00%
12-24 months | Series E Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	103.50%
12-24 months | Series F Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	103.50%
24-36 months | Series B Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	103.00%
Refinancing date | Series F Preferred
Class of Stock [Line Items]
Redemption rights (as a percent)	101.00%