Deferred Sales Commissions, Net

12 Months Ended

Dec. 31, 2017

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Deferred Sales Commissions, Net

Deferred Sales Commissions, Net

The components of deferred sales commissions, net for the years ended December 31, 2017 and 2016 were as follows (excluding amounts related to fully amortized deferred sales commissions):

	December 31,
	2017			2016
	(in thousands)
Carrying amount of deferred sales commissions	$	911,852		$	903,252
Less: Accumulated amortization	(597,566		)	(565,681		)
Cumulative CDSC received	(284,160		)	(273,681		)
Deferred sales commissions, net	$	30,126		$	63,890

Amortization expense was $31.9 million, $41.1 million and $49.1 million for the years ended December 31, 2017, 2016 and 2015, respectively. Estimated future amortization expense related to the December 31, 2017 net asset balance, assuming no additional CDSC is received in future periods, is as follows (in thousands):

2018	$	20,778
2019	6,343
2020	2,615
2021	344
2022	38
2023	8
	$	30,126