Investments and Fair Value Measurements (Details Textual) (USD $)	Sep. 30, 2012	Jan. 01, 2012
Investments and Fair Value Measurements
Cash	$ 334,100,000	$ 186,400,000
Assets, Fair Value Disclosure	5,087,831,000	5,454,454,000
Liabilities, Fair Value Disclosure	6,759,000	45,835,000
Fair Value, Assets, Level 1 to Level 2 Transfers, Amount	0
Fair Value, Assets, Level 2 to Level 1 Transfers, Amount	0
Fair Value, Liabilities, Level 1 to Level 2 Transfers, Amount	0
Fair Value, Liabilities, Level 2 to Level 1 Transfers, Amount	0
Fair Value, Inputs, Level 3 [Member]
Investments and Fair Value Measurements
Assets, Fair Value Disclosure	0	0
Liabilities, Fair Value Disclosure	$ 0	$ 0