Fair Value of Financial Instruments Additional Information about Level 3 Assets Measured at Fair Value on a Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 185,902	$ 451,979	$ 193,220
Total Realized and Unrealized Gains (Losses) Included in Income	(72,594)	(188,173)	(251,042)
Purchases	0	51,407	2,712
Sales	(63,400)	(138,077)	(17,904)
Issuances	12,471	15,541	10,540
Distributions and Other Settlements	(24)	(1,139)	(945)
Transfers Into Level 3	0	0	24,217
Transfers Out of Level 3	(2,422)	(381,982)	(10,903)
Ending Balance	137,208	185,902	451,979
Equity warrant assets | Other Assets
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	114,698	99,891	66,129
Total Realized and Unrealized Gains (Losses) Included in Income	(71,402)	(71,516)	(22,929)
Purchases	0	0	0
Sales	(61,044)	(70,875)	(16,680)
Issuances	12,471	15,541	10,540
Distributions and Other Settlements	63	345	98
Transfers Into Level 3	0	0	24,217
Transfers Out of Level 3	(2,422)	(1,720)	(7,342)
Ending Balance	135,168	114,698	99,891
Non-marketable securities | Fair value accounting
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	71,204	352,088	127,091
Total Realized and Unrealized Gains (Losses) Included in Income	(1,192)	(116,657)	(228,113)
Purchases	0	51,407	2,712
Sales	(2,356)	(67,202)	(1,224)
Issuances	0	0	0
Distributions and Other Settlements	(87)	(1,484)	(1,043)
Transfers Into Level 3	0	0	0
Transfers Out of Level 3	0	(380,262)	(3,561)
Ending Balance	2,040	71,204	352,088
Non-marketable securities | Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	71,204	32,839	127,091
Total Realized and Unrealized Gains (Losses) Included in Income	(1,192)	(12,793)	(5,745)
Purchases	0	51,407	2,712
Sales	(2,356)	(20,362)	(1,224)
Issuances	0	0	0
Distributions and Other Settlements	(87)	(5,347)	(97,924)
Transfers Into Level 3	0	0	0
Transfers Out of Level 3	0	(126)	(3,561)
Ending Balance	2,040	71,204	32,839
Non-marketable securities | Fair value accounting | Other investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	0	319,249	0
Total Realized and Unrealized Gains (Losses) Included in Income		(103,864)	(222,368)
Purchases		0	0
Sales		(46,840)	0
Issuances		0	0
Distributions and Other Settlements		3,863	96,881
Transfers Into Level 3		0	0
Transfers Out of Level 3		(380,136)	0
Ending Balance		0	$ 319,249
Accounting Standards Update 2015-02
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	117,989
Ending Balance		117,989
Accounting Standards Update 2015-02 | Non-marketable securities | Fair value accounting
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	3,291
Ending Balance		3,291
Accounting Standards Update 2015-02 | Non-marketable securities | Fair value accounting | Other venture capital investments
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Beginning Balance	$ 3,291
Ending Balance		$ 3,291