Subsequent Events - Additional Information (Detail) (USD $)	0 Months Ended		0 Months Ended		1 Months Ended	12 Months Ended	0 Months Ended
	Nov. 20, 2013	Dec. 31, 2013 Revolving Credit Facility [Member]	Feb. 20, 2014 Subsequent Event [Member]	Jan. 07, 2014 Subsequent Event [Member]	Feb. 28, 2014 Subsequent Event [Member] Revolving Credit Facility [Member]	Dec. 31, 2013 Subsequent Event [Member] Revolving Credit Facility [Member]	Jan. 07, 2014 Subsequent Event [Member] Partners Capital [Member]
Subsequent Event [Line Items]
Cash dividend per common share	$ 0.24		$ 0.29
Dividends Payable, Date Declared	Nov. 20, 2013		Feb. 13, 2014
Dividends Payable, Date of Record	Dec. 20, 2013		Mar. 20, 2014
Dividends Payable, Date to be Paid	Jan. 07, 2014		Apr. 08, 2014
Dividend paid to shareholders				$ 7,000,000			$ 2,000,000
Unsecured revolving credit facility					50,000,000	50,000,000
Unsecured Credit Facility maximum borrowing capacity		$ 350,000,000			$ 400,000,000	$ 400,000,000