Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 9,826	$ 9,695
Preferred stock, undesignated, par (in dollars per share)	$ 0.10	$ 0.10
Preferred stock, undesignated, shares authorized (in shares)	2,000,000	2,000,000
Preferred stock, undesignated, shares outstanding (in shares)	0	0
Common stock, par (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	125,000,000	125,000,000
Common stock, shares issues (in shares)	31,491,872	31,922,409
Common stock, shares outstanding (in shares)	31,491,872	31,922,409