Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Schedule of Available-for-sale Securities
Equity in loss of unconsolidated affiliate	$ (483)	$ (479)
Debt securities, Cost	8,194		8,909
Debt securities, Carrying Value	8,413		9,042
Total, Cost	19,552		23,689
Total, Gross Unrealized Gains	7,375		7,533
Total, Gross Unrealized Losses	(111)		(190)
Total, Carrying Value	26,816		31,032
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value	2,839		5,035
Less than 12 months, Gross Unrealized Loss	111		187
Greater than 12 months, fair value	0		9
Greater than 12 months, Gross Unrealized Loss	0		3
Available-for-sale Securities, Debt Maturities [Abstract]
Due in one year or less, Amortized Cost	3,781		3,786
Due after one year through five years, Amortized Cost	2,549		3,310
Due after five years, Amortized Cost	1,864		1,813
Due in one year or less, Carrying Value	3,941		3,958
Due after one year through five years, Carrying Value	2,548		3,255
Due after five years, Carrying Value	1,924		1,829
Corporate Bond Securities
Schedule of Available-for-sale Securities
Debt securities, Cost	8,194		8,909
Debt securities, Gross Unrealized Gains	239		198
Debt securities, Gross Unrealized Losses	(20)		(65)
Debt securities, Carrying Value	8,413		9,042
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value	1,996		3,228
Less than 12 months, Gross Unrealized Loss	20		65
Greater than 12 months, fair value
Greater than 12 months, Gross Unrealized Loss
Equity Securities
Schedule of Available-for-sale Securities
Marketable equity securities, Cost	11,358		14,780
Marketable equity securities, Gross Unrealized Gains	7,136		7,335
Marketable equity securities, Gross Unrealized Losses	(91)		(125)
Marketable equity securities, carrying value	18,403		21,990
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value	843		1,807
Less than 12 months, Gross Unrealized Loss	91		122
Greater than 12 months, fair value			9
Greater than 12 months, Gross Unrealized Loss			$ 3