Debt - Additional Information (Detail) (USD $)	12 Months Ended					3 Months Ended	1 Months Ended		3 Months Ended	7 Months Ended				1 Months Ended					1 Months Ended		1 Months Ended				1 Months Ended			3 Months Ended				12 Months Ended	1 Months Ended			1 Months Ended					3 Months Ended					1 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Interest Rate Contract	Dec. 31, 2011 Interest Rate Contract	Jun. 30, 2010 Interest Rate Contract One	Oct. 31, 2011 Interest Rate Contract Two	Apr. 26, 2011 2006 Senior Unsecured Notes	Oct. 31, 2011 2006 Senior Unsecured Notes	Jul. 30, 2011 2006 Senior Unsecured Notes	Dec. 31, 2006 2006 Senior Unsecured Notes	Oct. 31, 2011 LIBOR 2006 Senior Unsecured Notes	Jul. 30, 2011 LIBOR 2006 Senior Unsecured Notes	Apr. 30, 2011 Unsecured Senior Notes	Jun. 30, 2007 Collateralized Revolving Bank Credit Facility	Dec. 31, 2012 Collateralized Revolving Bank Credit Facility	Dec. 31, 2011 Collateralized Revolving Bank Credit Facility	Jun. 30, 2007 Collateralized Revolving Bank Credit Facility LIBOR	Feb. 17, 2012 2012 Senior Unsecured Notes	Dec. 31, 2012 2012 Senior Unsecured Notes	Mar. 09, 2012 2012 Term Loan	Mar. 09, 2012 2012 Term Loan LIBOR	Mar. 09, 2012 2012 Term Loan Federal Funds Rate	Mar. 09, 2012 2012 Term Loan Euro Dollar Rate	Jul. 31, 2011 Exchangeable Senior Notes	Apr. 30, 2008 Exchangeable Senior Notes	Mar. 31, 2008 Exchangeable Senior Notes	Sep. 30, 2011 Exchangeable Senior Notes	Dec. 31, 2012 Exchangeable Senior Notes	Dec. 31, 2011 Exchangeable Senior Notes	Aug. 31, 2011 Exchangeable Senior Notes	Dec. 31, 2011 Unsecured Senior Notes	Mar. 31, 2012 Unsecured Revolving Credit Facility	Dec. 31, 2012 Unsecured Revolving Credit Facility	Dec. 31, 2011 Unsecured Revolving Credit Facility	Mar. 31, 2012 Unsecured Revolving Credit Facility Minimum	Mar. 31, 2012 Unsecured Revolving Credit Facility Maximum	Mar. 31, 2012 Unsecured Revolving Credit Facility LIBOR Minimum	Mar. 31, 2012 Unsecured Revolving Credit Facility LIBOR Maximum	Mar. 31, 2012 Unsecured Revolving Credit Facility Federal Funds Rate	Jun. 30, 2010 2006 Senior Unsecured Notes	Dec. 31, 2012 2006 Senior Unsecured Notes	Dec. 31, 2011 2006 Senior Unsecured Notes	Dec. 31, 2012 Mortgages	Dec. 31, 2011 Mortgages	Feb. 14, 2011 Mortgages Northland Ltach Hospital Y	Dec. 31, 2012 Term Loans	Dec. 31, 2011 Term Loans
Debt Instrument [Line Items]
Senior Unsecured Notes											$ 125,000,000								$ 200,000,000
Interest rate								6.875%		7.871%									6.375%	6.375%						9.25%		9.25%	9.25%	9.25%																6.20%	6.20%	6.20%
Debt instrument maturity date								May 01, 2021											Feb. 15, 2022		Mar. 09, 2016					Apr. 01, 2013																				Jan. 01, 2018
Net proceeds, after underwriting discount																			196,500,000
Paid off term loan																					100,000,000
Private offering														450,000,000
Percentage of outstanding notes purchased from senior unsecured notes offering																									85.00%			86.60%
Senior notes, maturity year																												2013
Credit facilities, weighted average interest rate																1.80%	1.60%											118.40%						3.20%	3.20%
Price of principal amount plus accrued and unpaid interest, in amount																									84,200,000			84,100,000
Charge of refinancing activities																																14,200,000
Debt instrument face amount								450,000,000												200,000,000									11,000,000	11,000,000			70,000,000									125,000,000	125,000,000				14,200,000
Credit facilities, amount outstanding															42,000,000		39,600,000																	125,000,000	50,000,000	330,000,000	400,000,000
Credit facility, maturity date															2012-06																		2015-10
Credit facilities, basis spread of interest rate												2.30%	2.30%				1.80%	1.50%				2.25%	0.50%	1.00%										2.85%	2.85%	1.60%	2.40%	2.60%	3.40%	0.50%
Initial spread interest rate																					1.25%												1.60%
Credit facilities, percentage of commitment fee on unused capacity																																				0.375%	0.50%
Revolving facility agreement, availability																																		275,000,000
Credit facilities, repayment term															Five years
Credit facilities, remaining borrowing capacity																	0
Senior notes frequency of periodic payment								Semi-annually	Quarterly	Quarterly									Semi-annually
Senior notes, earliest redemption date								May 01, 2016											Feb. 15, 2017
Senior notes, repurchase price percentage on principal amount plus accrued and unpaid interest								101.00%											101.00%
Credit facilities, periodic payments of interest										65,000,000
Unsecured senior notes, year of maturity									2016-07	2016-07
Fixed rate, minimum									7.333%
Fixed rate, maximum									7.715%
Portion of debt instrument face amount																																									65,000,000
Fair value of the interest rate swaps				12,500,000	12,200,000
Interest rate of interest rate derivative instrument						5.507%
Maturity date of interest rate swap						July 2016	October 2016
Interest rate swap, amount fixed							60,000,000
Interest rate of derivative instrument							5.675%
Hedge ineffectiveness and income statement effect in period	0	0	0
Other assets, collateral	6,600,000	6,300,000
Senior Notes																										7,000,000	75,000,000				1,500,000
Proceeds from senior notes																										6,800,000	72,800,000
Exchange price of notes per common share																										$ 12.36
Price of principal amount plus accrued and unpaid interest, in percentage																									118.50%
Term loan facility, potential term extension period																					1 year
Term loan facility, extension option maturity date																					Mar. 09, 2017
Liabilities acquired																																														14,600,000
Amortization period																																														30
Debt instrument earliest prepayment date																																														Jan. 01, 2013
Collateralized real estate property																																												$ 17,200,000	$ 17,600,000
Percentage of dividends which could be paid from adjusted operating funds	105.00%
Restricted percentage for dividend payment for next year	95.00%
Percentage of dividends which could be paid from operation funds	95.00%
Maximum percentage of total unencumbered assets	150.00%	150.00%