Other intangible assets

3 Months Ended

Mar. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Other intangible assets consist of the following as of March 31, 2017:



	Favorable lease assets	Internet sites	Trade names	Total
	$'000	$'000	$'000	$'000

Carrying amount:
Balance at January 1, 2017	8,501	1,658	7,579	17,738
Additions	—	—	—	—
Foreign currency translation adjustment	50	26	493	569

Balance at March 31, 2017	8,551	1,684	8,072	18,307

Accumulated amortization:
Balance at January 1, 2017	2,636	1,225		3,861
Charge for the period	92	41		133
Foreign currency translation adjustment	17	20		37

Balance at March 31, 2017	2,745	1,286		4,031

Net book value:
At March 31, 2017	5,806	398	8,072	14,276

At December 31, 2016	5,865	433	7,579	13,877

Favorable lease intangible assets are amortized over the terms of the leases, which are between 19 and 60 years. Internet sites are amortized over a period of five to ten years. Trade names have an indefinite life and therefore are not amortized, but are assessed for impairment annually or when events indicate that impairment may have occurred.

Amortization expense for the three months ended March 31, 2017 was $133,000 (March 31, 2016 - $123,000). Estimated total amortization expense for the remainder of the year ending December 31, 2017 is $399,000 and for each of the years ending December 31, 2018 to December 31, 2021 is $532,000.