Stockholders' Equity and EPS - Reconciliation of Basic EPS to Diluted EPS (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014
Numerator:
Net income available to common stockholders	[1]	$ 86,143	$ 50,953	$ 174,659	[2]	$ 141,903
Denominator:
Weighted average common shares outstanding-basic (in shares)		51,268	48,168	51,139		47,025
Denominator for diluted calculation (in shares)		51,876	49,045	51,788		47,987
Earnings per common share:
Basic (dollars per share)	[1]	$ 1.68	$ 1.06	$ 3.42	[2]	$ 3.02
Diluted (dollars per share)		$ 1.66	$ 1.04	$ 3.37	[2]	$ 2.96
Stock options and ESPP
Denominator:
Weighted average effect of dilutive securities (in shares)		410	569	420		601
Restricted stock units
Denominator:
Weighted average effect of dilutive securities (in shares)		198	308	229		361

[1] Prior period amounts have been revised to reflect the retrospective application of new accounting guidance adopted in the first quarter of 2015 related to our investments in qualified affordable housing projects (ASU 2014-01). See Note 1— "Basis of Presentation" of the "Notes to Interim Consolidated Financial Statements" under Part I, Item 1 in this report.

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