Investments (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		$ 2,907	$ 12,981
Gross Unrealized Gains			616
Gross Unrealized Losses
Fair Value		2,907	13,597
Auction Rate Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost			1,175
Gross Unrealized Gains			615
Gross Unrealized Losses
Fair Value			1,790
Sale proceeds	1,800
Gross gains	600
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost		2,907	11,806
Gross Unrealized Gains			1
Gross Unrealized Losses
Fair Value		$ 2,907	$ 11,807