Loans and Allowance for Loan Losses - Carrying Amounts at Acquisition of All Purchased Loans (Impaired and Non-Impaired) Acquired (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Accretable yield	$ (74,322)	$ (37,078)
Acquired Loans [Member] | BCSB Bancorp, Inc. (BCSB) [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition	680,058
Non-accretable difference (expected losses and foregone interest)	(33,740)
Cash flows expected to be collected at acquisition	646,318
Accretable yield	(125,001)
Basis in acquired loans at acquisition	521,317
Acquired Loans [Member] | BCSB Bancorp, Inc. (BCSB) [Member] | Impaired Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition	16,679
Non-accretable difference (expected losses and foregone interest)	(8,299)
Cash flows expected to be collected at acquisition	8,380
Accretable yield	(1,214)
Basis in acquired loans at acquisition	7,166
Acquired Loans [Member] | BCSB Bancorp, Inc. (BCSB) [Member] | Performing Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition	663,379
Non-accretable difference (expected losses and foregone interest)	(25,441)
Cash flows expected to be collected at acquisition	637,938
Accretable yield	(123,787)
Basis in acquired loans at acquisition	514,151
Acquired Loans [Member] | Annapolis Bancorp Inc. And PVF Capital Corp. [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition		837,086
Non-accretable difference (expected losses and foregone interest)		(76,199)
Cash flows expected to be collected at acquisition		760,887
Accretable yield		(115,352)
Basis in acquired loans at acquisition		645,535
Acquired Loans [Member] | Annapolis Bancorp Inc. And PVF Capital Corp. [Member] | Impaired Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition		40,972
Non-accretable difference (expected losses and foregone interest)		(23,207)
Cash flows expected to be collected at acquisition		17,765
Accretable yield		(2,505)
Basis in acquired loans at acquisition		15,260
Acquired Loans [Member] | Annapolis Bancorp Inc. And PVF Capital Corp. [Member] | Performing Loans [Member]
Certain Loans Acquired in Transfer Not Accounted for as Debt Securities Acquired During Period [Line Items]
Contractually required cash flows at acquisition		796,114
Non-accretable difference (expected losses and foregone interest)		(52,992)
Cash flows expected to be collected at acquisition		743,122
Accretable yield		(112,847)
Basis in acquired loans at acquisition		$ 630,275