Supplemental Condensed Consolidated Financial Information Supplemental Condensed Consolidated Financial Information (Condensed Consolidating Balance Sheets) (Parenthetical) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, allowance for doubtful accounts	$ 2,450	$ 2,450
Common stock, shares issued	54,063,705	52,880,134
Consolidating Adjustments [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Common stock, shares issued	0	0
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, allowance for doubtful accounts	$ 0	$ 0
Common stock, shares issued	54,063,705	52,880,134
Combined Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, allowance for doubtful accounts	$ 1,245	$ 1,245
Common stock, shares issued	0	0
Combined Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Accounts receivable, allowance for doubtful accounts	$ 1,205	$ 1,205
Common stock, shares issued	0	0