Fair Value Measurements (Details) (USD $)	Fair Value Measurements Using Unadjusted Quoted Market Prices (Level 1) Equity Securities	Fair Value Measurements Using Quoted Prices for Identical or Similar Assets in Active Markets (Level 2) Other Investment	Fair Value Measurements Using Significant Unobservable Inputs (Level 3) Long-Term Equity Funding Agreements
Balance. at Dec. 31, 2013	$ 21,320	$ 10,000	$ 55,943
Total gains or losses Included in earnings (or changes in net assets)	1,303	1,410	0
Purchases	18,846	0	0
Issuances	0	0	0
Sales	(35,637)	(1,150)	0
Settlements	0	0	0
Balance. at Dec. 31, 2014	5,832	10,260	55,943
Total gains or losses Included in earnings (or changes in net assets)	1,278	152	0
Purchases	1,061	0	0
Issuances	0	0	0
Sales	(1,053)	(1,150)	0
Settlements	0	0	0
Balance. at Mar. 31, 2015	$ 7,118	$ 10,412	$ 55,943