Investments - Schedule of Investments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Schedule of Available-for-sale Securities [Line Items]
Cost	$ 115,410
Gross Unrealized Gains	18
Gross Unrealized Losses	909
Fair Value	114,519
U.S. treasury securities
Schedule of Available-for-sale Securities [Line Items]
Cost	84,964
Gross Unrealized Gains	18
Gross Unrealized Losses	0
Fair Value	84,982
Corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Cost	30,446
Gross Unrealized Gains	0
Gross Unrealized Losses	909
Fair Value	$ 29,537

Amount 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