XML 67 R56.htm IDEA: XBRL DOCUMENT v3.10.0.1
Fair Value Measurements - Additional Information (Details) - USD ($)
9 Months Ended
Sep. 30, 2018
Sep. 20, 2018
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Escrow cash $ 604,100,000  
Fair value assets, Level 1 to Level 2 transfers amount 0  
Fair value assets, Level 2 to Level 1 transfers amount $ 0  
6% Senior Notes due 2026    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Interest rate (as a percent) 6.00% 6.00%
6% Senior Notes due 2026 | Level 1    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]    
Interest rate (as a percent) 6.00%  
Escrow cash $ 600,000,000  
Debt interest placed in to escrow $ 4,100,000