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Information Concerning Guarantor and Non-Guarantor Subsidiaries - General Information (Details)
12 Months Ended
Dec. 31, 2018
USD ($)
entity
Apr. 15, 2015
USD ($)
Apr. 03, 2013
USD ($)
Condensed Financial Statements, Captions [Line Items]      
Number of wholly-owned subsidiaries | entity 4    
Ownership percentage in subsidiaries (as a percent) 100.00%    
Senior Notes [Member] | $350 Million 5% Senior Notes [Member]      
Condensed Financial Statements, Captions [Line Items]      
Face amount $ 350,000,000   $ 350,000,000
Stated interest rate (as a percent) 5.00%   5.00%
Senior Notes [Member] | $400 Million 5% Senior Notes [Member]      
Condensed Financial Statements, Captions [Line Items]      
Face amount $ 400,000,000 $ 400,000,000  
Stated interest rate (as a percent) 5.00% 5.00%