Stockholders' Equity - Summary of Dividend Distributions (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 0.00	$ 0.00	$ 0.00
Total Dividend/ Distribution	$ 18,947	$ 19,565	$ 19,677
Common Class A [Member]
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 0.0000	$ 0.0000	$ 0.0000
Total Dividend/ Distribution
Series F Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 5,455.88910	$ 6,510.90280	$ 6,736.15400
Total Dividend/ Distribution	2,728	3,256	3,368
Series G Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 7,236.00000	$ 7,236.00000	$ 7,236.00000
Total Dividend/ Distribution	1,809	1,809	1,809
Series J Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 18,125.20000	$ 18,125.20000	$ 18,125.20000
Total Dividend/ Distribution	10,785	10,875	10,875
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Dividend/ Distribution per Share/ Unit	$ 18,125.20000	$ 18,125.20000	$ 18,125.20000
Total Dividend/ Distribution	$ 3,625	$ 3,625	$ 3,625