Fair Value - Changes in Fair Value in Financial Liabilities (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013		Dec. 31, 2013	Dec. 31, 2012
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	$ 10,548,793		$ 11,478,563		$ 10,129,658	$ 11,977,174
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liability, Debt Eliminations	15,394		3,937
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances	750,966		332,250
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	573,166		936,194
Net realized gains from debt	357		(7,603)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	11,153		101,667
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	316,252
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	70,319
Debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	10,422,320		11,347,332		9,994,147	11,834,955
Fair Value, Measurement With Unobservable Inputs Reconciliation, Recurring Basis, Liability, Debt Eliminations	15,394		3,937
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances	750,966		332,250
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	558,608		911,775
Net realized gains from debt	357		(7,603)
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	5,633		88,236
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3	316,252
Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers out of Level 3	70,319
Contingent Consideration Obligations
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	126,473		131,231		135,511	142,219
Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements	14,558		24,419
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	5,520	[1]	13,431	[1]
Variable Interest Entity, Primary Beneficiary | Net Gains (Losses) from Investment Activities
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	4,996		87,186
Variable Interest Entity, Primary Beneficiary | Net Gains (Losses) from Investment Activities | Debt
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value, Liabilities Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 4,996		$ 87,186

[1] Changes in fair value of contingent consideration obligations are recorded in profit sharing expense in the condensed consolidated statements of operations.