Notes Payable and Borrowings under Capital Leases - Components of Company's Notes Payable and Borrowings under Capital Leases Balances (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Line of Credit Facility [Abstract]
Notes payable under credit facility	$ 494,501	$ 499,563
Deferred loan costs	(5,178)	(5,781)
Capital leases	142	153
Less current portion	(35,358)	(32,970)
Notes payable and borrowings under capital leases, less current portion	$ 454,107	$ 460,965