Basis of Presentation (Investment Categories) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2012
Summary of investment categories
Cost	$ 2,767	$ 2,767
Gross unrealized gains	2,201
Gross unrealized losses
Estimated fair value	4,968	2,767
Available-for-sale securities [Member]
Summary of investment categories
Cost	1,426	1,426
Gross unrealized gains	2,201
Gross unrealized losses
Estimated fair value	3,627	1,426
Certificates of deposit - restricted [Member]
Summary of investment categories
Cost	1,341	1,341
Gross unrealized gains
Gross unrealized losses
Estimated fair value	$ 1,341	$ 1,341