Short- and Long-Term Investments and Investments on Deposit for Licensure (Details 1) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012
Amortized cost and fair value of available-for-sale debt securities by contractual maturity
Maturing within one year, amortized cost	$ 456,138
Maturing within one year, fair value	456,893
Maturing between one year and five years, amortized cost	604,792
Maturing between one year and five years, fair value	610,121
Maturing between five years and ten years, amortized cost	206,261
Maturing between five years and ten years, fair value	216,985
Maturing in greater than ten years, amortized cost	49,631
Maturing in greater than ten years, fair value	52,212
Total, amortized cost	1,316,822
Total, fair value	$ 1,336,211

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