Fair Value Disclosures (Narrative) (Details) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2014	Dec. 31, 2013
Mortgage notes and related accrued interest receivable	$ 490,840,000	$ 486,337,000
Investment in a direct financing lease, net	242,905,000	242,212,000
Finance lease investment weighted average interest rate	12.01%
Minimum interest on investments in direct finance lease	11.74%
Maximum interest on investments in direct finance lease	12.38%
Debt	1,482,608,000	1,475,336,000
Fixed Rate Mortgage Notes Receivable [Member]
Mortgage notes and related accrued interest receivable	490,800,000	486,300,000
Weighted average interest rate of mortgage notes receivable	9.08%	9.05%
Receivable interest rate minimum	5.50%	5.50%
Receivable interest rate maximum	11.31%	11.31%
Weighted market rate used for determining future cash flow for notes receivable	10.14%	10.12%
Fair value of notes receivable	470,500,000	465,200,000
Variable Rate Debt [Member]
Debt	300,000,000	290,000,000
Long-term debt, weighted average interest rate	1.61%	1.62%
Variable Rate Converted to Fixed Rate [Member]
Debt	240,000,000	240,000,000
Fixed Rate Debt [Member]
Debt	1,180,000,000	1,190,000,000
Long-term debt, weighted average interest rate	6.10%	6.10%
Weighted market rate for determining fair value of debt	4.03%	4.85%
Fair value of debt	1,290,000,000
Long-term Debt, Fair Value		$ 1,240,000,000
Minimum [Member] | Fixed Rate Mortgage Notes Receivable [Member]
market rate used as discount factor to determine fair value of notes	9.00%	9.00%
Minimum [Member] | Fixed Rate Debt [Member]
market rate used as discount factor to determine fair value of debt	2.13%	2.63%
Maximum [Member] | Fixed Rate Mortgage Notes Receivable [Member]
market rate used as discount factor to determine fair value of notes	11.31%	11.31%
Maximum [Member] | Fixed Rate Debt [Member]
market rate used as discount factor to determine fair value of debt	4.77%	5.56%