Fair Value Measurement (Details) (Starburst II, Inc. [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	$ 0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Gain (Loss) Included in Other Comprehensive Income (Loss)	160,100
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Accretion Of Impairment Included In Earnings	11,900
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Change in Fair Value	(175,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	3,101,000	3,104,000
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	3,101,000	3,104,000
Investments, Fair Value Disclosure	3,101,000	2,929,000
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Derivative Assets		175,000
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	0	0
Investments, Fair Value Disclosure	0	0
Cash and Cash Equivalents, Fair Value Disclosure	0	0
Derivative Assets		0
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	11,461	5,000
Investments, Fair Value Disclosure	0	0
Cash and Cash Equivalents, Fair Value Disclosure	11,461	5,000
Derivative Assets		0
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	3,112,461	3,109,000
Investments, Fair Value Disclosure	3,101,000	2,929,000
Cash and Cash Equivalents, Fair Value Disclosure	11,461	5,000
Derivative Assets		175,000
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Gain (Loss) Included in Other Comprehensive Income (Loss)	0
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Accretion Of Impairment Included In Earnings	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Change in Fair Value	(175,000)
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	0	175,000
Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers, Net	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Gain (Loss) Included in Other Comprehensive Income (Loss)	160,100
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Accretion Of Impairment Included In Earnings	11,900
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Change in Fair Value	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales	0
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value	$ 3,101,000	$ 2,929,000