Long-Term Debt - Components of Long-Term Debt (Details) - USD ($) $ in Thousands	Sep. 30, 2015		Dec. 31, 2014
Components of Long-term debt
Long-term debt	$ 403,604		$ 198,000
Current portion of long-term debt	6,792		2,000
Long-term debt (less current portion)	396,812		196,000
Fair value of long-term debt	400,800	[1]	194,000
Unsecured subordinated notes payable
Components of Long-term debt
Long-term debt	8,104		0
Variable rate credit facility
Components of Long-term debt
Long-term debt	0		0
Term loan
Components of Long-term debt
Long-term debt	$ 395,500		$ 198,000

[1] * Fair value of the term loan was estimated based on quoted private market transactions and is classified as Level 1 in the fair value hierarchy