Intangible Assets (Amortization Expense of Core Deposit Intangible Assets) (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
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Carrying amount	$ 13,865	$ 10,243	$ 13,865	$ 10,243	$ 15,388
Amortization of intangible assets			2,794	2,935
Core deposit intangible assets [Member]
Carrying amount, accumulated amortization and amortization expense of core deposit intangible assets
Gross original amount	18,659	26,468	18,659	26,468	18,659
Accumulated amortization	8,193	19,691	8,193	19,691	6,749
Carrying amount	10,466	6,777	10,466	6,777	11,910
Amortization of intangible assets	$ 467	$ 367	$ 1,444	$ 1,102