Summary of Significant Accounting Policies (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013 item	Dec. 31, 2012
Description of Business
Number of business segments	1
Investment Holdings
Total assets	$ 1,153,843	$ 1,097,532
All Non-United States countries
Investment Holdings
Total assets	0
Revenue	$ 0