Investments and Fair Value Measurements-AFS FV and Unrealized Losses (Details 5) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	$ 1,386,657
Less than 12 months, Gross Unrealized Loss	(8,699)
U.S. Treasury and government agency securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	24,294
Less than 12 months, Gross Unrealized Loss	(1)
U.S. Government-sponsored agency securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	5,763
Less than 12 months, Gross Unrealized Loss	(23)
International Government Securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	2,976
Less than 12 months, Gross Unrealized Loss	(24)
Corporate notes and bonds [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	334,887
Less than 12 months, Gross Unrealized Loss	(1,159)
Asset-backed securities [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	120,003
Less than 12 months, Gross Unrealized Loss	(332)
Mortgage Backed Securities, Other [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	1,508
Less than 12 months, Gross Unrealized Loss	(25)
Municipal notes and bonds [Member]
Available-for-sale securities that were in an unrealized gain position
Less than 12 months, Fair Value	897,226
Less than 12 months, Gross Unrealized Loss	$ (7,135)