5. Long-Lived Assets

Property, plant and equipment consisted of the following (dollars in thousands):

	September 30,			December 31,
	2013			2012

Property, plant and equipment	$	705,519		$	639,343
Less accumulated depreciation and amortization	(187,645		)	(132,146		)

	$	517,874		$	507,197

Depreciation expense amounted to $19.3 million and $56.5 million for the three and nine months ended September 30, 2013, respectively. Depreciation expense amounted to $17.3 million and $49.9 million for the three and nine months ended September 30, 2012, respectively.

In February 2013, the Company entered into an agreement to sell a parcel of land and warehouse not actively used in the Company’s operations for a purchase price of $13.9 million. The sale was subject to due diligence by the buyer and approval of the Hawaii Public Utilities Commission (“HPUC”). The HPUC approval was received in May 2013 and the sale was consummated in June 2013. The net proceeds, net of commissions and other costs paid through escrow of $0.8 million, amounted to $13.1 million. A gain on the sale of $6.5 million was recognized in the second quarter of 2013 as management concluded the land sold was not grouped with the assets subject to the composite depreciation method. The HPUC approval requires the Company to spend $0.3 million on training employees on broadband telecommunication deployment and operation. In addition, the HPUC approval provides for the Company to make improvements to its broadband network in an amount equal to the net proceeds less the training cost commitment. The planned training expenses and network capital spending will be recognized as the costs are incurred.

In January 2013, the Company entered into an agreement to sell most of its radio towers for $3.6 million. The sale was subject to due diligence by the buyer. In November 2013, the buyer, as a result of a change in its ownership, issued a termination notice of the purchase per the provisions of the agreement.

The gross carrying amount and accumulated amortization of identifiable intangible assets are as follows (dollars in thousands):

	September 30, 2013						December 31, 2012
	Gross						Gross
	Carrying		Accumulated		Net Carrying		Carrying		Accumulated		Net Carrying
	Value		Amortization		Value		Value		Amortization		Value

Subject to amortization —
Customer relationships	$	21,709	$	8,194	$	13,515	$	17,850	$	6,285	$	11,565
Trade name and other	320		83		237		210		—		210
	22,029		8,277		13,752		18,060		6,285		11,775
Not subject to amortization —
Brand name	27,300		—		27,300		27,300		—		27,300
	27,300		—		27,300		27,300		—		27,300

	$	49,329	$	8,277	$	41,052	$	45,360	$	6,285	$	39,075

Amortization expense amounted to $0.7 million and $2.0 million for the three and nine months ended September 30, 2013, respectively. Amortization expense amounted to $0.7 million and $2.1 million for the three and nine months ended September 30, 2012, respectively. Estimated amortization expense for the next five years and thereafter is as follows (dollars in thousands):

2013 (remaining months)	$	828
2014	2,896
2015	2,498
2016	2,100
2017	1,703
Thereafter	3,727

	$	13,752

With the acquisition of SystemMetrics, the Company recognized customer relationship intangibles of $3.6 million with a useful life of 13 years and a trade name of $0.1 million with a useful life of four years. The determination of useful lives for customer relationships was based on historical and expected customer attrition rates. The Company will use an accelerated amortization method reflecting the rate of expected customer attrition.

In conjunction with the acquisition of Wavecom, the Company adjusted the carrying value of goodwill in the first quarter of 2013 as further discussed in Note 3. The revised goodwill amounted to $1.4 million and is included in the wireline segment. In conjunction with the acquisition of SystemMetrics, the Company recognized goodwill of $10.4 million which is expected to be attributed to the data center colocation services segment.