Intangible Assets (Net Carrying Value) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Net carrying value of intangible assets
Goodwill	$ 180,128	$ 180,128	$ 120,164
Other intangible assets:
Total other intangible assets	31,655	33,080	12,872
Core deposit intangible assets [Member]
Other intangible assets:
Total other intangible assets	20,072	20,863	9,556
Mortgage servicing rights [Member]
Other intangible assets:
Total other intangible assets	$ 11,583	$ 12,217	$ 3,316	$ 3,423