Loans (Schedule of the Allowance for Loan Losses) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	$ 82,184	$ 86,711	$ 84,491	$ 88,333
Provision for loan losses	3,000	4,500	9,000	13,500
Charge-offs	(4,430)	(7,596)	(15,265)	(20,315)
Recoveries	778	1,079	3,306	3,176
Ending balance	81,532	84,694	81,532	84,694
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses	4,223	8,659	4,223	8,659	8,108
Loans collectively evaluated for impairment related to allowance for loan losses	76,809	75,535	76,809	75,535	75,883
Loans acquired with deteriorated credit quality related to allowance for loan losses	500	500	500	500	500
Total	81,532	84,694	81,532	84,694
Loans individually evaluated for impairment related to recorded investment (loan balance)	96,513	104,053	96,513	104,053	106,228
Loans collectively evaluated for impairment related to recorded investment (loan balance)	4,117,215	3,502,494	4,117,215	3,502,494	3,668,912
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)	308,943	412,612	308,943	412,612	392,595
Total loans	4,522,671	4,019,159	4,522,671	4,019,159	4,167,735
Commercial Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	47,780	53,759	49,975	55,645
Provision for loan losses	2,810	2,365	5,815	6,003
Charge-offs	(2,637)	(4,754)	(9,374)	(11,330)
Recoveries	374	460	1,911	1,512
Ending balance	48,327	51,830	48,327	51,830
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses	3,638	8,010	3,638	8,010	7,450
Loans collectively evaluated for impairment related to allowance for loan losses	44,689	43,820	44,689	43,820	42,525
Loans acquired with deteriorated credit quality related to allowance for loan losses	0	0	0	0	0
Total	48,327	51,830	48,327	51,830
Loans individually evaluated for impairment related to recorded investment (loan balance)	78,782	84,495	78,782	84,495	87,327
Loans collectively evaluated for impairment related to recorded investment (loan balance)	2,105,006	1,721,367	2,105,006	1,721,367	1,840,629
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)	261,999	354,031	261,999	354,031	336,864
Total loans	2,445,787	2,159,893	2,445,787	2,159,893	2,264,820
Consumer Loan Portfolio [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	28,745	29,784	29,333	29,166
Provision for loan losses	2,165	1,765	4,684	7,481
Charge-offs	(1,793)	(2,842)	(5,891)	(8,985)
Recoveries	404	619	1,395	1,664
Ending balance	29,521	29,326	29,521	29,326
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses	585	649	585	649	658
Loans collectively evaluated for impairment related to allowance for loan losses	28,436	28,177	28,436	28,177	28,175
Loans acquired with deteriorated credit quality related to allowance for loan losses	500	500	500	500	500
Total	29,521	29,326	29,521	29,326
Loans individually evaluated for impairment related to recorded investment (loan balance)	17,731	19,558	17,731	19,558	18,901
Loans collectively evaluated for impairment related to recorded investment (loan balance)	2,012,209	1,781,127	2,012,209	1,781,127	1,828,283
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)	46,944	58,581	46,944	58,581	55,731
Total loans	2,076,884	1,859,266	2,076,884	1,859,266	1,902,915
Unallocated [Member]
Schedule of allowance and recorded investment related to financing receivables segregated by portfolio segment
Beginning balance	5,659	3,168	5,183	3,522
Provision for loan losses	(1,975)	370	(1,499)	16
Charge-offs	0	0	0	0
Recoveries	0	0	0	0
Ending balance	3,684	3,538	3,684	3,538
Allowance for loan losses
Loans individually evaluated for impairment related to allowance for loan losses	0	0	0	0	0
Loans collectively evaluated for impairment related to allowance for loan losses	3,684	3,538	3,684	3,538	5,183
Loans acquired with deteriorated credit quality related to allowance for loan losses	0	0	0	0	0
Total	3,684	3,538	3,684	3,538
Loans individually evaluated for impairment related to recorded investment (loan balance)	0	0	0	0	0
Loans collectively evaluated for impairment related to recorded investment (loan balance)	0	0	0	0	0
Loans acquired with deteriorated credit quality related to recorded investment (loan balance)	0	0	0	0	0
Total loans	$ 0	$ 0	$ 0	$ 0	$ 0