Investments and Fair Value Measurements (Gains (Losses) on Investments) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Available-for-sale:
Available-for-sale securities, Cost	$ 11,596		$ 11,596		$ 90,560
Available-for-sale Securities, Unrealized Gain	849		849		1,269
Available-for-sale Securities, Unrealized Loss	(219)		(219)		(368)
Available-for-sale securities, Fair Value	12,226		12,226		91,461
Held-to-maturity:
Held-to-maturity securities, Cost	18,059		18,059		31,214
Held-to-maturity Securities, Unrecognized Gain	0		0		0
Held-to-maturity Securities, Unrecognized Loss	0		0		0
Held-to-maturity	18,059		18,059		31,214
Available-for-sale Securities, Gross Realized Gain (Loss) [Abstract]
Available-for-sale securities, realized gains	158	94	731	2,320
Available-for-sale securities, realized losses	0	(136)	(226)	(1,214)
Available-for-sale securities, realized gains (losses), net	158	(42)	505	1,106
Government Obligations [Member]
Available-for-sale:
Available-for-sale securities, Cost	0		0		19,693
Available-for-sale Securities, Unrealized Gain	0		0		8
Available-for-sale Securities, Unrealized Loss	0		0		(3)
Available-for-sale securities, Fair Value	0		0		19,698
Corporate Bonds [Member]
Available-for-sale:
Available-for-sale securities, Cost	0		0		49,913
Available-for-sale Securities, Unrealized Gain	0		0		22
Available-for-sale Securities, Unrealized Loss	0		0		(124)
Available-for-sale securities, Fair Value	0		0		49,811
Foreign Government Debt Securities [Member]
Available-for-sale:
Available-for-sale securities, Cost	0		0		505
Available-for-sale Securities, Unrealized Gain	0		0		0
Available-for-sale Securities, Unrealized Loss	0		0		(2)
Available-for-sale securities, Fair Value	0		0		503
Commercial Paper [Member]
Available-for-sale:
Available-for-sale securities, Cost	0		0		9,482
Available-for-sale Securities, Unrealized Gain	0		0		7
Available-for-sale Securities, Unrealized Loss	0		0		0
Available-for-sale securities, Fair Value	0		0		9,489
Equity Securities and Exchange-traded Funds [Member]
Available-for-sale:
Available-for-sale securities, Cost	6,499		6,499		8,872
Available-for-sale Securities, Unrealized Gain	477		477		1,011
Available-for-sale Securities, Unrealized Loss	(81)		(81)		(141)
Available-for-sale securities, Fair Value	6,895		6,895		9,742
Mutual Funds [Member]
Available-for-sale:
Available-for-sale securities, Cost	5,097		5,097		2,095
Available-for-sale Securities, Unrealized Gain	372		372		221
Available-for-sale Securities, Unrealized Loss	(138)		(138)		(98)
Available-for-sale securities, Fair Value	$ 5,331		$ 5,331		$ 2,218

Held-to-maturity Securities, Accumulated Unrecognized Holding Gain

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Held-to-maturity Securities, Accumulated Unrecognized Holding Loss

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Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

+ References

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 2

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt and equity securities classified as available-for-sale.

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This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

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-Subparagraph (SX 210.5-02.2)

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Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

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-Publisher FASB

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This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities.

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This item represents the gross profit realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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This item represents the gross loss realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities.

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Amount before other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity.

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Amount after other than temporary impairment (OTTI) accretion, of investments in debt securities classified as held-to-maturity, expected to be converted to cash, sold or exchanged within one year or the normal operating cycle.

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