Derivative Financial Instruments (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Derivative [Line Items]    
Derivatives contracts $ 434,034 $ 362,917
Forward rate commitments    
Derivative [Line Items]    
Derivatives contracts 294,746 240,574
Interest rate lock commitments    
Derivative [Line Items]    
Derivatives contracts $ 139,288 $ 122,343