Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value assets measured on recurring basis	$ 33,574	$ 29,782
Fair value liabilities measured on recurring basis	44,300	36,267
Cash surrender value of life insurance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value assets measured on recurring basis	33,574	29,782
Contingent consideration liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	3,134	4,584
Deferred compensation liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	34,742	30,336
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	6,424	1,347
Fair Value, Inputs, Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value assets measured on recurring basis	33,574	29,782
Fair value liabilities measured on recurring basis	41,166	31,683
Fair Value, Inputs, Level 2 | Cash surrender value of life insurance
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value assets measured on recurring basis	33,574	29,782
Fair Value, Inputs, Level 2 | Deferred compensation liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	34,742	30,336
Fair Value, Inputs, Level 2 | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	6,424	1,347
Fair Value, Inputs, Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	3,134	4,584
Fair Value, Inputs, Level 3 | Contingent consideration liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis
Fair value liabilities measured on recurring basis	$ 3,134	$ 4,584