Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash Flows from Operating Activities
Net income	$ 149,221	$ 35,504	$ 52,271
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	146,523	206,270	266,975
Amortization of debt issuance costs	1,068	1,123	1,576
Deferred income taxes	(147,329)	(25,118)	(22,745)
Provision for credit losses	32,077	30,092	24,214
Provision for service credits	32,550	25,467	31,491
Stock-based compensation (benefit) expense	(2,895)	14,119	39,604
Other components of net periodic pension cost	42,236	53,161	516
Loss on early extinguishment of debt	0	6,375	18,375
Loss on disposal/write-off of fixed assets and capitalized software	3,544	5,942	11,464
Impairment charges	24,911	5,670	0
Non-cash loss (gain) from remeasurement of indemnification asset	5,443	4,093	(9,518)
Changes in working capital items, excluding acquisitions:
Accounts receivable	41,382	16,457	14,456
Contract assets	369	1,515	(4,834)
Prepaid and other assets	472	5,676	(3,019)
Accounts payable and accrued liabilities	(100,708)	(69,244)	(72,112)
Accrued income taxes, net	14,547	4,376	(12,797)
Operating lease liability	(4,006)	(10,587)	0
Contract liabilities	(5,737)	(6,391)	11,144
Settlement of stock option liability	(896)	(33,901)	0
Net cash provided by operating activities	232,772	270,599	347,061
Cash Flows from Investing Activities
Additions to fixed assets and capitalized software	(27,757)	(26,065)	(27,429)
Proceeds from the sale of building and fixed assets	1,546	847	17
Acquisition of a business, net of cash acquired	0	(147)	(1,250)
Net cash (used in) investing activities	(26,211)	(25,365)	(28,662)
Cash Flows from Financing Activities
Payments of Senior Term Loan	(113,747)	(148,256)
Payments of Senior Term Loan, related party	(46,643)	(66,744)	(130,226)
Proceeds from Senior Term Loan, net	0	193,625	381,625
Proceeds from Senior Term Loan, related party	0	225,000	0
Payments of Original Term Facility, upon extinguishment			198,973
Payments of Original Term Facility, upon extinguishment, related party			(155,368)
Payments of Original Term Facility, prior to extinguishment			(166,774)
Proceeds from ABL Facility	1,143,700	1,142,717	1,823,207
Payments of ABL Facility	(1,169,446)	(1,184,310)	(1,836,642)
Purchase of treasury stock	(30,626)	(437,962)	0
Other	10,695	(1,561)	(3,117)
Net cash (used in) financing activities	(206,067)	(277,491)	(286,268)
Increase (decrease) in cash and cash equivalents	494	(32,257)	32,131
Cash and cash equivalents, beginning of period	1,912	34,169	2,038
Cash and cash equivalents, end of period	2,406	1,912	34,169
Supplemental Information
Interest expense	72,931	81,543	80,972
Cash paid for income taxes, net	$ 24,799	$ 38,091	$ 44,029