Fair Value Measurements (Fair Value Measurement Inputs) (Details) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Balance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	$ 360,455	$ 178,756
Restricted cash	17,170	15,753
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	360,455	178,756
Restricted cash	17,170	15,753
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash	0	0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash and cash equivalents	0	0
Restricted cash	$ 0	$ 0