Premises and Equipment (Details) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Premises and equipment
Total	$ 284,012,000	$ 180,732,000
Less accumulated depreciation	(95,898,000)	(65,149,000)
Net premises and equipment	188,114,000	115,583,000
Depreciation expense charged to operations	10,000,000	8,700,000	7,800,000
Amortization expense	1,400,000	1,300,000	928,000
Land
Premises and equipment
Total	67,056,000	30,522,000
Buildings and leasehold improvements
Premises and equipment
Total	145,028,000	98,500,000
Buildings and leasehold improvements | Minimum
Premises and equipment
Useful Life	15 years
Buildings and leasehold improvements | Maximum
Premises and equipment
Useful Life	40 years
Equipment and furnishings
Premises and equipment
Total	70,989,000	50,538,000
Equipment and furnishings | Minimum
Premises and equipment
Useful Life	3 years
Equipment and furnishings | Maximum
Premises and equipment
Useful Life	10 years
Construction in process
Premises and equipment
Total	939,000	1,172,000
Computer software
Premises and equipment
Useful Life	36 months
Total	$ 10,700,000	$ 8,900,000