Investment Securities - Investments in Debt and Equity Securities Reported Less than Historical Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Fair value	$ 23,184	$ 177,584
Investments reported at less than historical cost
Schedule of Investments [Line Items]
Historical cost	23,406	178,964
Fair value	$ 23,184	$ 177,584
Percent of the Corporation's available for sale and held to maturity portfolio	1.80%	13.90%