Preferred Stock - Additional Information (Detail) (USD $)	3 Months Ended	12 Months Ended				12 Months Ended			12 Months Ended			12 Months Ended			12 Months Ended			3 Months Ended
	Sep. 14, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Sep. 30, 2012	Dec. 31, 2013 Cumulative Series D Six Percent Non-Qualified Preferred Stock [Member]	Dec. 30, 2013 Cumulative Series D Six Percent Non-Qualified Preferred Stock [Member]	Dec. 31, 2012 Cumulative Series D Six Percent Non-Qualified Preferred Stock [Member]	Dec. 31, 2013 Cumulative Series E Eighteen Point Seven Five Percent Nonvoting Preferred Stock [Member]	Dec. 30, 2013 Cumulative Series E Eighteen Point Seven Five Percent Nonvoting Preferred Stock [Member]	Dec. 31, 2012 Cumulative Series E Eighteen Point Seven Five Percent Nonvoting Preferred Stock [Member]	Dec. 31, 2013 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Dec. 31, 2012 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Sep. 14, 2012 Cumulative Series C Six Point Seven Five Percent Redeemable Perpetual Preferred Stock [Member]	Dec. 31, 2013 Series B Subordinated Non-Voting Cumulative Redeemable Preferred Stock	Dec. 31, 2012 Series B Subordinated Non-Voting Cumulative Redeemable Preferred Stock	Dec. 31, 2011 Series B Subordinated Non-Voting Cumulative Redeemable Preferred Stock	Dec. 31, 2012 Cumulative Series Eight Point Zero Three Four Percent Redeemable Perpetual Preferred Stock [Member]	Oct. 18, 2012 Cumulative Series Eight Point Zero Three Four Percent Redeemable Perpetual Preferred Stock [Member]
Auction Market Preferred Securities, Stock Series [Line Items]
Preferred Stock, shares authorized		10,000,000
Preferred Stock, par value per share		$ 0.01	$ 0.01			$ 0.01		$ 0.00	$ 0.01		$ 0.00	$ 0.01	$ 0.01
Stock issued for acquisition properties															0	0	3,480,000
Preferred Stock, Dividend Rate, Percentage						6.00%			18.75%			6.75%
Perpetual Preferred OP Units conversion		$ 0	$ 0	$ (200,000,000)
Common Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01
At The Market Offering Value					125,000,000
Preferred Stock, Shares Authorized		9,945,164	9,945,539			125	125	0	250	250	0	54,461	54,461	54,458
Preferred Stock, Liquidation Preference Per Share							$ 1,000.00			$ 1,000.00				$ 2,500.00					$ 25.00
Peferred Stock, Shares Exchanged	5,445,765
Depositary Shares, Issued	5,445,765
Depositary Share, Liquidation Preference Per Share	$ 25.00
Preferred Stock, Dividend Rate, Per-Dollar-Amount	$ 0.3849625																	$ 0.0948460
Stock Redeemed or Called During Period, Shares																		2,554,235
Stock Redeemed or Called During Period, Value																		$ 64,100,000