Common Stock and Other Equity Related Transactions - Additional Information (Detail) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Apr. 10, 2015
6.75% Series C Cumulative Redeemable Perpetual Preferred Stock
Class of Stock [Line Items]
Date to be paid	Mar. 31, 2015
Preferred stock dividends paid (usd per share)	$ 0.421875
Date of record	Mar. 20, 2015
Subsequent Event | Common Stock
Class of Stock [Line Items]
Date to be paid		Apr. 10, 2015
Date of record		Mar. 27, 2015
Common Stock dividends paid (usd per share)		$ 0.375