Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 3,268	$ 3,661
Accumulated depreciation	212,882	188,720
Accumulated amortization	$ 19,446	$ 12,655
Common stock, $0.01 par value	$ 0.01	$ 0.01
Common stock shares authorized	100,000	100,000
Common stock shares issued	43,125	42,914
Treasury stock shares	485	438