Securities (Details 2) (USD $) In Thousands, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	$ 786,183	$ 184,146
Less Than 12 Months, Unrealized Losses	23,201	2,562
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	786,183	184,146
Total Unrealized Losses	23,201	2,562
Obligations of U.S. Government sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	316,509	1,147
Less Than 12 Months, Unrealized Losses	6,853	2
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	316,509	1,147
Total Unrealized Losses	6,853	2
Obligations of U.S. states and political subdivisions
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	30,641	10,307
Less Than 12 Months, Unrealized Losses	1,235	73
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	30,641	10,307
Total Unrealized Losses	1,235	73
Residential Mortgage-backed securities U.S. Government agencies
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	63,312	40,022
Less Than 12 Months, Unrealized Losses	2,348	548
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	63,312	40,022
Total Unrealized Losses	2,348	548
Residential Mortgage-backed securities U.S. Government sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	372,386	128,365
Less Than 12 Months, Unrealized Losses	12,600	1,768
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	372,386	128,365
Total Unrealized Losses	12,600	1,768
U.S. corporate debt securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	2,387	2,487
Less Than 12 Months, Unrealized Losses	113	13
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	2,387	2,487
Total Unrealized Losses	113	13
Equity securities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value	948	985
Less Than 12 Months, Unrealized Losses	52	15
12 Months Or Longer, Fair Value	0	0
12 Months Or Longer, Unrealized Losses	0	0
Total Fair Value	948	985
Total Unrealized Losses	52	15
Residential Mortgage-backed securities Non-U.S. Government agencies or sponsored entities
Schedule of Available-for-sale Securities [Line Items]
Less Than 12 Months, Fair Value		833
Less Than 12 Months, Unrealized Losses		143
12 Months Or Longer, Fair Value		0
12 Months Or Longer, Unrealized Losses		0
Total Fair Value		833
Total Unrealized Losses		$ 143