Components of Secured Loans,Unsecured Notes Payable and Line of Credit (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014 HUD Loan	Dec. 31, 2013 HUD Loan	Jun. 15, 2012 HUD Loan	Sep. 30, 2014 2019 Notes	Dec. 31, 2013 2019 Notes	Mar. 28, 2012 2019 Notes	Apr. 05, 2011 2019 Notes	Sep. 30, 2014 2021 Notes	Dec. 31, 2013 2021 Notes	Sep. 30, 2014 Unsecured Revolving Credit Facility	Dec. 31, 2013 Revolving Credit Facility
Debt Instrument [Line Items]
Interest rate of debt	5.00%	5.00%		7.75%	7.75%			6.00%	6.00%	1.85%
Premium paid on issuance of senior notes	$ 2.40	$ 2.40	$ 2.50	$ 2.40	$ 2.80	$ 1.00	$ 2.75
Interest rate of debt				7.75%					6.00%		2.52%