Loans and Allowance for Loan Losses, Allowance for Loan Losses and Recorded Investment in Loans Based on Impairment Method (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013		Mar. 31, 2013	Dec. 31, 2012		Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011
Allowance for loan losses [Abstract]
Individually evaluated for impairment	$ 0			$ 0
Collectively evaluated for impairment	47,589			47,927
Total ending allowance balance	47,589		47,658	47,927		48,018	48,535	48,717
Loans [Abstract]
Individually evaluated for impairment	25,365			26,073
Collectively evaluated for impairment	2,737,061			2,658,660
Total ending loans balance	2,762,426			2,684,733
Commercial [Member]
Allowance for loan losses [Abstract]
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	3,719			3,771
Total ending allowance balance	3,719		3,964	3,771		3,792	3,602	4,140
Loans [Abstract]
Individually evaluated for impairment	6,474			9,333
Collectively evaluated for impairment	210,503			210,244
Total ending loans balance	216,977			219,577
Real Estate Mortgage - 1 to 4 Family [Member]
Allowance for loan losses [Abstract]
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	43,766			44,069
Total ending allowance balance	43,766		43,595	44,069		44,147	44,851	44,479
Loans [Abstract]
Individually evaluated for impairment	18,891			16,740
Collectively evaluated for impairment	2,521,014			2,443,837
Total ending loans balance	2,539,905			2,460,577
Installment [Member]
Allowance for loan losses [Abstract]
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	104			87
Total ending allowance balance	104		99	87		79	82	98
Loans [Abstract]
Individually evaluated for impairment	0			0
Collectively evaluated for impairment	5,544			4,579
Total ending loans balance	5,544			4,579
New York and Other States [Member]
Loans [Abstract]
Total ending loans balance	2,374,209	[1]		2,355,966	[1]
New York and Other States [Member] | Commercial [Member]
Loans [Abstract]
Total ending loans balance	195,556			200,630
New York and Other States [Member] | Installment [Member]
Loans [Abstract]
Total ending loans balance	4,910	[1]		4,183	[1]
Florida [Member]
Loans [Abstract]
Total ending loans balance	388,217			328,767
Florida [Member] | Commercial [Member]
Loans [Abstract]
Total ending loans balance	21,421			18,947
Florida [Member] | Installment [Member]
Loans [Abstract]
Total ending loans balance	$ 634			$ 396

[1] Includes New York, New Jersey, Vermont and Massachusetts.