CONDENSED CONSOLIDATING FINANCIAL INFORMATION - Statements of Comprehensive Income (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2014
Sep. 30, 2014
Jun. 30, 2014
Mar. 31, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Net earnings (loss) $ 28,973 $ 30,436 $ 23,967 $ 28,291 $ 29,819 $ 7,376 $ 31,393 $ (4,508) $ 111,667 $ 103,856 $ 64,080
Unrealized foreign currency translation adjustment, net of tax                 (3,881) 1,372 978
Pension and other benefit adjustments:                      
Net loss arising during the period, net of tax                 (293) 166 (13,543)
Prior service credit arising during the period, net of tax                   746  
Amortization of net (gain) loss reclassified into general and administrative: other, net of tax                 16 (1,679) (844)
Amortization of prior service credit reclassified into general and administrative: other, net of tax                   (1,762) (1,016)
Curtailment gain reclassified into general and administrative: other, net of tax                   (7,239)  
Settlement gain reclassified into general and administrative: other, net of tax                 (3) (196)  
Marketable securities:                      
Unrealized holding gains arising during the period, net of tax                 589 (1,056) 2,627
Realized net (gain) loss reclassified into investment income, net of tax                 (1,816) (156) (31)
Equity method investees' cash flow hedge:                      
Unrealized holding gains arising during the period                 (309) (693) (59)
Realized net loss reclassified into equity in earnings of non-consolidated entities, net of tax                 342 457 528
Other comprehensive income (loss), net of tax                 (5,355) (10,040) (11,360)
Total comprehensive income                 106,312 93,816 52,720
Consolidating Adjustments                      
Net earnings (loss)                 (152,401) (92,381) (49,496)
Equity in other comprehensive income (loss) of subsidiaries                 8,984 9,488 10,628
Equity method investees' cash flow hedge:                      
Other comprehensive income (loss), net of tax                 8,984 9,488 10,628
Total comprehensive income                 (143,417) (82,893) (38,868)
AMCEH                      
Net earnings (loss)                 111,667 103,856 64,080
Equity in other comprehensive income (loss) of subsidiaries                 (5,355) (10,040) (11,360)
Equity method investees' cash flow hedge:                      
Other comprehensive income (loss), net of tax                 (5,355) (10,040) (11,360)
Total comprehensive income                 106,312 93,816 52,720
Subsidiary Guarantors                      
Net earnings (loss)                 119,732 93,375 51,401
Equity in other comprehensive income (loss) of subsidiaries                 (3,629) 552 732
Unrealized foreign currency translation adjustment, net of tax                 (181) 820 246
Pension and other benefit adjustments:                      
Net loss arising during the period, net of tax                 (364) 166 (13,543)
Prior service credit arising during the period, net of tax                   746  
Amortization of net (gain) loss reclassified into general and administrative: other, net of tax                 16 (1,679) (844)
Amortization of prior service credit reclassified into general and administrative: other, net of tax                   (1,762) (1,016)
Curtailment gain reclassified into general and administrative: other, net of tax                   (7,239)  
Settlement gain reclassified into general and administrative: other, net of tax                 (3) (196)  
Marketable securities:                      
Unrealized holding gains arising during the period, net of tax                 589 (1,056) 2,627
Realized net (gain) loss reclassified into investment income, net of tax                 (1,816) (156) (31)
Equity method investees' cash flow hedge:                      
Unrealized holding gains arising during the period                 (309) (693) (59)
Realized net loss reclassified into equity in earnings of non-consolidated entities, net of tax                 342 457 528
Other comprehensive income (loss), net of tax                 (5,355) (10,040) (11,360)
Total comprehensive income                 114,377 83,335 40,041
Subsidiary Non-Guarantors                      
Net earnings (loss)                 32,669 (994) (1,905)
Unrealized foreign currency translation adjustment, net of tax                 (3,700) 552 732
Pension and other benefit adjustments:                      
Net loss arising during the period, net of tax                 71    
Equity method investees' cash flow hedge:                      
Other comprehensive income (loss), net of tax                 (3,629) 552 732
Total comprehensive income                 $ 29,040 $ (442) $ (1,173)