XML 89 R75.htm IDEA: XBRL DOCUMENT v3.8.0.1
Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]      
Impairment charges $ 1,511,000 $ 0 $ 0
Amortization of intangible assets 45,743,000 35,681,000 $ 6,764,000
Amortization income from unfavorable lease commitments $ 811,000 $ 569,000