Notes Receivable - Additional Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014 Note	Mar. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of notes receivable	2
Interest income	$ 3,031,000	$ 3,051,000
National Bonds [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of notes receivable	2
Interest income	3,000,000	3,000,000
Payment received relating to notes receivables	$ 3,500,000	$ 3,500,000