Acquisitions - Summary of Pro Forma Information Company's Results of Operations (Details) (USD $)
In Thousands, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Weighted average shares outstanding:    
Convertible Cumulative Participating Preferred Stock 4,008,439  
Customer Relationships (EHI)    
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]    
Net revenues $ 378,696 $ 379,270
Net income attributable to common stockholders $ 18,626 $ 17,684
Net income per share attributable to common stockholders:    
Basic, dollars per share $ 1.35 $ 1.61
Diluted, dollars per share $ 1.35 $ 1.61
Weighted average shares outstanding:    
Basic 13,768,836 [1] 10,989,466 [1]
Diluted 13,793,844 [1] 10,989,466 [1]
[1] Weighted average shares outstanding for the purposes of the above pro forma calculation assume the Convertible Redeemable Preferred Stock of 4,008,439 shares converted to the same number of shares of common stock at the beginning of the period presented.