Summary of Significant Accounting Policies (Adoption of New Accounting Standards) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
New Accounting Pronouncement, Early Adoption [Line Items]
Long term debt unamortized debt issuance costs	$ 4,900	$ 4,800
Other assets	47,741	47,399
Long-term debt, less current maturities	557,849	508,002
Current maturities of long-term debt	$ 6,113	6,043
As Reported on Form 10-K
New Accounting Pronouncement, Early Adoption [Line Items]
Other assets		52,241
Long-term debt, less current maturities		512,287
Current maturities of long-term debt		6,600
Decrease to the As Reported Balance | New Accounting Pronouncement, Early Adoption, Effect [Member]
New Accounting Pronouncement, Early Adoption [Line Items]
Other assets		(4,842)
Long-term debt, less current maturities		(4,285)
Current maturities of long-term debt		$ (557)