Investments (Investments Classified as Available-For-Sale) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 104,924	$ 12,981
Gross Unrealized Gains	34	616
Gross Unrealized Losses	(7)
Fair Value	104,951	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
Asset-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	42,478
Gross Unrealized Gains	8
Gross Unrealized Losses	(3)
Fair Value	42,483
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	62,446	11,806
Gross Unrealized Gains	26	1
Gross Unrealized Losses	(4)
Fair Value	$ 62,468	$ 11,807