Restricted Investments Contractual Maturities of Our Held-to-Maturity Restricted Investments (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014
Investments, Debt and Equity Securities [Abstract]
Amortized Cost, Due in one year or less	$ 76,957
Amortized Cost, Due one year through five years	5,079
Amortized Cost, Total	82,036
Estimated Fair Value, Due in one year or less	76,963
Estimated Fair Value, Due one year through five years	5,083
Estimated Fair Value, Total	$ 82,046