Common Stock and Other Equity Related Transactions - Additional Information (Detail) (USD $)	3 Months Ended
	Jun. 30, 2013 Common Stock	Mar. 31, 2013 Common Stock	Jun. 30, 2013 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Mar. 31, 2013 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Sep. 30, 2012 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Sep. 30, 2013 Subsequent Event [Member]
Class of Stock [Line Items]
Dividends Payable, Date to be Paid	Jul. 12, 2013	Apr. 12, 2013	Jul. 01, 2013	Apr. 01, 2013
Common Stock, Dividends, Per Share, Cash Paid	$ 0.25	$ 0.25
Preferred Stock, Dividends, Per Share, Cash Paid			$ 0.421875		$ 0.421875
Dividends Payable, Date of Record	Jun. 28, 2013	Mar. 28, 2013	Jun. 20, 2013	Mar. 21, 2013
Stockholders' Equity Note, Stock Split						On June 25, 2013, management announced a two-for-one split, to be effected by and in the form of a stock dividend, to take effect on July 15, 2013. On July 15, 2013, each common shareholder of record on July 5, 2013, received one additional share of common stock for each share held. On July 15, 2013, a two-for-one stock split of our common stock, effected by and in the form of a stock dividend, was paid to stockholders of record on July 5, 2013.
Stockholders' Equity Note, Stock Split, Conversion Ratio						2