Fair Value of Financial Instruments - Quantitative Information About Significant Unobservable Inputs (Detail) (USD $) In Thousands, unless otherwise specified											6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended			6 Months Ended	12 Months Ended			6 Months Ended	12 Months Ended
	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2014 Equity warrant assets Other assets	Mar. 31, 2014 Equity warrant assets Other assets	Jun. 30, 2013 Equity warrant assets Other assets	Mar. 31, 2013 Equity warrant assets Other assets	Jun. 30, 2014 Level 3 Other venture capital investments Fair value accounting	Dec. 31, 2013 Level 3 Other venture capital investments Fair value accounting	Jun. 30, 2014 Level 3 Other securities Fair value accounting	Dec. 31, 2013 Level 3 Other securities Fair value accounting	Jun. 30, 2014 Level 3 Equity warrant assets Investments [Member]	Dec. 31, 2013 Level 3 Equity warrant assets Investments [Member]	Jun. 30, 2014 Level 3 Equity warrant assets Other assets	Dec. 31, 2013 Level 3 Equity warrant assets Other assets	Jun. 30, 2014 Level 3 Equity Warrant Asset, Private Portfolio [Member] Investments [Member]	Dec. 31, 2013 Level 3 Equity Warrant Asset, Private Portfolio [Member] Investments [Member]	Jun. 30, 2014 Level 3 Equity Warrant Asset, Private Portfolio [Member] Other assets	Dec. 31, 2013 Level 3 Equity Warrant Asset, Private Portfolio [Member] Other assets	Jun. 30, 2014 Fair Value, Measurements, Recurring Other securities Fair value accounting	Mar. 31, 2014 Fair Value, Measurements, Recurring Other securities Fair value accounting	Dec. 31, 2013 Fair Value, Measurements, Recurring Other securities Fair value accounting	Dec. 31, 2013 Fair Value, Measurements, Recurring Equity warrant assets Other assets	Dec. 31, 2012 Fair Value, Measurements, Recurring Equity warrant assets Other assets
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Fair value	$ 1,177,228	$ 1,455,357	$ 1,314,951	$ 938,244	$ 891,908	$ 859,141	$ 87,151	$ 87,642	$ 73,229	$ 66,046	$ 43,747	$ 32,839	$ 5,808	$ 319,249	$ 671	$ 24,217			$ 86,480	$ 75,674			$ 5,808	$ 362,487	$ 319,249	$ 99,891	$ 66,129
Fair Value Inputs, Weighted Average Discount for Sales Restrictions													10.00%	12.00%			14.80%	13.70%
Valuation Technique											Private company equity pricing	Private company equity pricing	Modified stock price	Modified stock price			Modified Black-Scholes option pricing model	Modified Black-Scholes option pricing model			Modified Black-Scholes option pricing model	Modified Black-Scholes option pricing model
Volatility																	43.30%	41.30%			38.90%	40.10%
Risk-Free interest rate																	1.80%	1.70%			0.80%	0.80%
Marketability discount																					20.00%	22.50%
Remaining life assumption																					45.00%	45.00%