Stockholders' Equity - Additional Information (Detail) - USD ($)			3 Months Ended		6 Months Ended	12 Months Ended
		Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 18, 2015	Dec. 30, 2014	Sep. 27, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Value, Issued					$ 0	$ 0	$ 70,500,000				$ 141,000,000
Preferred Stock, Shares Issued					70,500	70,500	141,000			141,000,000	141,000,000
Preferred Stock, Par or Stated Value Per Share					$ 0.0001	$ 0.0001	$ 0.0001				$ 0.0001
Preferred Stock, Liquidation Preference Per Share					$ 1,000	$ 1,000	$ 1,000		$ 1,000		$ 1,000
Preferred Stock, Shares Outstanding						70,500	70,500
Preferred Stock, Redemption Amount							$ 70,700,000		$ 70,700,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options					$ 18,500,000	$ 18,500,000
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range, Outstanding Options, Weighted Average Remaining Contractual Term						2 years 2 months 9 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value						$ 3,600,000	$ 7,100,000	$ 2,800,000
Common Stock, Shares, Issued					103,087,044	103,087,044	88,691,249
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						509,000	508,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number					1,492,000	1,492,000	1,050,000	1,204,000
Weighted Average Selling Price Per Share						$ 38.13
Proceeds from Issuance of Common Stock, Gross						$ 29,000,000
Stock Issued During Period, Value, New Issues						28,288,000	$ 13,746,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering Cost from Issuance of Common Stock						$ 700,000	$ 500,000
Stock Issued During Period, Shares, New Issues				760,376		760,000	548,122
Weighted Average Selling Price Per Share							$ 25.96
Stock Issued During Period, Value, New Issues							$ 14,200,000.0
Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred Stock, Shares Outstanding						71,000	70,000
Performance Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			285,000			308,400
Allocated Share-based Compensation Expense						$ 4,800,000	$ 3,600,000
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense						$ 9,300,000	$ 6,800,000
Bridge Capital Holdings [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Acquisition Share Exchange Ratio		0.8145
Business Acquisition Cash Consideration Per Share		$ 2.39
Equity Award Conversion Ratio		0.905
Business Combination, Consideration Transferred, Liabilities Incurred		$ 10,676,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		$ 2,400,000
Common Stock, Shares, Issued		12,451,240			12,451,240	12,451,240
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period						546,000	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid		213,091
Stock Issued During Period, Value, New Issues	[1]					$ 431,031,000
Business Combination, Consideration Transferred, Equity Interests Issued and Issuable		$ 420,354,000
Payments to Acquire Businesses, Gross		$ 36,539,000
Bridge Capital Holdings [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Issued During Period, Shares, New Issues						12,997,000
Stock Issued During Period, Value, New Issues	[1]					$ 1,000
Bridge Capital Holdings [Member] | Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate		0.00%
Business Combination, Consideration Transferred, Liabilities Incurred		$ 1,713,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		$ 4,100,000
Allocated Share-based Compensation Expense					$ 500,000
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate		33.96%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate		2.11%
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term		7 years 7 months 28 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 19.06
Bridge Capital Holdings [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Business Combination, Consideration Transferred, Liabilities Incurred		$ 8,963,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options		17,000,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options		$ 8,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		546,151
Allocated Share-based Compensation Expense					$ 1,700,000

[1] Includes value of certain share-based awards replaced in connection with the acquisition.