Marketable Securities - Maturities of Held to Maturity Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012
Marketable Securities [Abstract]
Held-to-maturity investments, maturities due within one year	$ 70,444
Held-to-maturity investments, maturities due in one to five years	70,114
Held-to-maturity investments, total maturities due	$ 140,558

This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature after one year and through five years from the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details

This item represents debt securities, at cost, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments, as defined), and fair value hedge accounting adjustments, if any, which are expected to mature within one year of the balance sheet date and which are categorized as held-to-maturity.

+ References+ Details