Line of Credit (Details) (USD $)	3 Months Ended		1 Months Ended	3 Months Ended			3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013 Unsecured Debt [Member] U.S. Bank and East-West Bank [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 Unsecured Debt [Member] U.S. Bank and East-West Bank [Member] Revolving Credit Facility [Member]	Mar. 31, 2014 Unsecured Debt [Member] U.S. Bank and East-West Bank [Member] Revolving Credit Facility [Member] Minimum [Member]	Mar. 31, 2014 Unsecured Debt [Member] U.S. Bank and East-West Bank [Member] Revolving Credit Facility [Member] Maximum [Member]	Mar. 31, 2014 Unsecured Debt [Member] U.S. Bank and East-West Bank [Member] Revolving Credit Facility [Member] LIBOR [Member]
Line of Credit Facility [Line Items]
Increase in maximum borrowing capacity			$ 40,000,000.0
Maximum borrowing capacity			140,000,000.0
Basis spread on variable rate							2.75%
Rent adjusted fixed charge coverage ratio				3.01	1.50
Balance sheet leverage ratio				0.82		1.50
Covenant, tangible net worth				905,700,000	250,000,000
Line Of Credit Facility Covenant Compliance Minimum Requirement Of Unrestricted Cash Cash Equivalents And Publicly Traded Marketable Securities				1,573,100,000	40,000,000
Borrowings under line of credit	90,000,000	35,000,000		90,000,000
Maximum amount drawn on the unsecured credit facility at any one point				90,000,000
Remaining borrowing capacity				$ 140,000,000