Investment Income and Other (Schedule Of Investment Income and Other) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended							12 Months Ended			15 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012
Gain on payoff of mortgage note receivable								$ 4,605	$ 0	$ 0
Gains on sales of marketable securities								30	9,899	0
Other gains								242	362	272
Investment income and other	$ 4,759	$ 46	$ 35	$ 37	$ 1,114	$ 8,661	$ 192	$ 4,877	$ 10,261	$ 272	$ 294