Investments (Available-For-Sale Investments) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 84,849	$ 67,702
Gross Unrealized Gains	1,168	931
Gross Unrealized Losses	100	145
Fair Market Value	85,917	68,488
Money Market Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	551	1,989
Fair Market Value	551	1,989
Mortgage-Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,934	3,017
Gross Unrealized Gains	109	61
Gross Unrealized Losses		18
Fair Market Value	3,043	3,060
Corporate Bonds And Direct Obligations Of Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	68,368	51,014
Gross Unrealized Gains	1,018	819
Gross Unrealized Losses	97	126
Fair Market Value	69,289	51,707
U.S. Treasury Obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	12,996	11,682
Gross Unrealized Gains	41	51
Gross Unrealized Losses	3	1
Fair Market Value	$ 13,034	$ 11,732

For an unclassified balance sheet, total of debt securities categorized neither as held-to-maturity nor trading.

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+ Details

- Definition

This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

+ References+ Details