Leases and Commitments - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Leased Assets [Line Items]
Lease expense	$ 20,360,000	$ 23,568,000	$ 24,726,000
Buildings and equipment capitalized under capital leases	42,640,000	12,123,000
Accumulated amortization in connection with capital leases	$ 7,667,000	$ 7,143,000
Minimum
Operating Leased Assets [Line Items]
Lease term	1 year
Maximum
Operating Leased Assets [Line Items]
Lease term	20 years