Goodwill - Additional Information (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Goodwill and Intangible Assets Disclosure [Abstract]      
Goodwill $ 216,930,000 $ 222,460,000 $ 222,460,000
Goodwill adjustment 5,530,000    
Goodwill, impairment 0 0  
Goodwill, acquired $ 0 $ 0