Quarterly report pursuant to Section 13 or 15(d)

Basis of presentation (Details)

v3.7.0.1
Basis of presentation (Details)
$ in Thousands
3 Months Ended
Jul. 14, 2016
segment
Feb. 20, 2015
contract
Mar. 31, 2017
USD ($)
segment
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Interim Consolidated Financial Information          
Number of operating segments | segment 1   2    
Deferred income taxes     $ 55,336   $ 54,563
Derivative Number of Contracts | contract   3      
Litigation proceeds       $ 10,050  
Accounting Standards Update 2015-17 [Member]          
Interim Consolidated Financial Information          
Deferred income taxes     $ 5,726   $ 5,726
Interest Rate Swap Effective 31 December 2015 through 29 March 2018          
Interim Consolidated Financial Information          
Fixed interest rate (as a percent)     6.105%    
Interest Rate Swap Effective 31 December 2015 through 29 March 2018 | London Interbank Offered Rate (LIBOR)          
Interim Consolidated Financial Information          
Interest rate added to variable rate (as a percent)     4.25%    
LIBOR floor (as a percent)     1.00%    
Interest Rate Swap Effective 29 March 2018 through 31 March 2020          
Interim Consolidated Financial Information          
Fixed interest rate (as a percent)     6.916%    
Interest Rate Swap Effective 29 March 2018 through 31 March 2020 | London Interbank Offered Rate (LIBOR)          
Interim Consolidated Financial Information          
Interest rate added to variable rate (as a percent)     4.25%    
LIBOR floor (as a percent)     1.00%    
Interest Rate Swap Effective 31 March 2020 through 30 June 2021          
Interim Consolidated Financial Information          
Fixed interest rate (as a percent)     7.168%    
Interest Rate Swap Effective 31 March 2020 through 30 June 2021 | London Interbank Offered Rate (LIBOR)          
Interim Consolidated Financial Information          
Interest rate added to variable rate (as a percent)     4.25%    
LIBOR floor (as a percent)     1.00%