Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Financial information for the Company's operating segments
Net interest income	$ 49,971	$ 33,381
Provision for loan losses	1,450	3,050
Noninterest income	18,616	17,335
Noninterest expense	47,645	37,557
Income before income taxes	19,492	10,109
Income taxes	5,895	2,538
Net income	13,597	7,571
Total assets	5,902,831	4,267,658	5,746,270
Goodwill	276,144	184,779	276,100
Community Banks
Financial information for the Company's operating segments
Net interest income	50,636	33,677
Provision for loan losses	1,389	2,917
Noninterest income	14,083	14,547
Noninterest expense	44,125	35,059
Income before income taxes	19,205	10,248
Income taxes	5,978	2,723
Net income	13,227	7,525
Total assets	5,826,289	4,205,826
Goodwill	273,387	181,996
Insurance
Financial information for the Company's operating segments
Net interest income	63	23
Provision for loan losses	0	0
Noninterest income	2,393	1,033
Noninterest expense	1,474	813
Income before income taxes	982	243
Income taxes	380	94
Net income	602	149
Total assets	17,442	10,214
Goodwill	2,757	2,783
Wealth Management
Financial information for the Company's operating segments
Net interest income	311	295
Provision for loan losses	61	133
Noninterest income	2,116	1,734
Noninterest expense	1,868	1,581
Income before income taxes	498	315
Income taxes	0	0
Net income	498	315
Total assets	44,345	39,673
Goodwill	0	0
Other
Financial information for the Company's operating segments
Net interest income	(1,039)	(614)
Provision for loan losses	0	0
Noninterest income	24	21
Noninterest expense	178	104
Income before income taxes	(1,193)	(697)
Income taxes	(463)	(279)
Net income	(730)	(418)
Total assets	14,755	11,945
Goodwill	$ 0	$ 0