Stockholders' Equity - Dividend Distributions (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Class of Stock [Line Items]
Distributions Per Share	$ 0.085	$ 0
Total Dividend/Distribution	$ 9,536
Total Dividend/Distribution	3,837
Common Stock
Class of Stock [Line Items]
Distributions Per Share	$ 0.085
Total Dividend/Distribution	9,536
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/Distribution per Share	$ 1,331.25
Total Dividend/Distribution	666
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/Distribution per Share	$ 1,809.00
Total Dividend/Distribution	452
Series J Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/Distribution per Share	$ 4,531.30
Total Dividend/Distribution	1,813
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/Distribution per Share	$ 4,531.30
Total Dividend/Distribution	$ 906