Stockholders' Equity and EPS - Reconciliation of Basic EPS to Diluted EPS (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Numerator:
Net income available to common stockholders (1)	$ 88,516	$ 90,950	[1],[2]
Denominator:
Weighted average common shares outstanding-basic (in shares)	51,009	45,866
Denominator for diluted calculation (in shares)	51,719	46,725
Earnings per common share:
Basic (dollars per share)	$ 1.74	$ 1.98	[1],[2]
Diluted (dollars per share)	$ 1.71	$ 1.95
Stock options and ESPP
Denominator:
Weighted average effect of dilutive securities (in shares)	445	566
Restricted stock units
Denominator:
Weighted average effect of dilutive securities (in shares)	265	293

[1] Results for the quarter ended March 31, 2014 were restated to reflect the retrospective application of adopting new accounting guidance in 2015 related to our investments in qualified affordable housing projects (ASU 2014-01). See Note 1 of the Notes to Consolidated Financial Statements for additional information.

[2] 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.