Summary of Significant Accounting Policies - Customer Relationships and Acquisition Costs and Other Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amortizable intangible assets
Amortization of Intangible Assets	$ 44,245	$ 48,586	$ 39,181
Amortization Expense Included In Depreciation And Amortization [Member]
Estimated amortization expense for existing intangible assets for the next five succeeding fiscal years
2016	45,763
2017	45,012
2018	44,139
2019	42,666
2020	40,831
Amortization Expense Charged To Revenues [Member]
Estimated amortization expense for existing intangible assets for the next five succeeding fiscal years
2016	7,445
2017	5,526
2018	4,296
2019	2,491
2020	$ 1,704
Customer relationship intangible assets | Minimum
Amortizable intangible assets
Useful life of finite-lived intangible assets	10 years
Customer relationship intangible assets | Maximum
Amortizable intangible assets
Useful life of finite-lived intangible assets	30 years
Customer relationship intangible assets | Weighted Average
Amortizable intangible assets
Useful life of finite-lived intangible assets	20 years
Initial Costs For Transport Of Boxes | Minimum
Amortizable intangible assets
Useful life of finite-lived intangible assets	1 year
Initial Costs For Transport Of Boxes | Maximum
Amortizable intangible assets
Useful life of finite-lived intangible assets	30 years
Initial Costs For Transport Of Boxes | Weighted Average
Amortizable intangible assets
Useful life of finite-lived intangible assets	25 years
Customer Relationships Current Record Management Vendor Or Payments To Customers | Minimum
Amortizable intangible assets
Useful life of finite-lived intangible assets	1 year
Customer Relationships Current Record Management Vendor Or Payments To Customers | Maximum
Amortizable intangible assets
Useful life of finite-lived intangible assets	15 years
Customer Relationships Current Record Management Vendor Or Payments To Customers | Weighted Average
Amortizable intangible assets
Useful life of finite-lived intangible assets	6 years
Other Intangible Assets
Amortizable intangible assets
Gross carrying amount	$ 11,111	10,630
Accumulated amortization	8,325	8,608
Other Intangible Assets | Amortization Expense Included In Depreciation And Amortization [Member]
Amortizable intangible assets
Amortization of Intangible Assets	$ 631	1,853	1,456
Other Intangible Assets | Minimum
Amortizable intangible assets
Useful life of finite-lived intangible assets	5 years
Other Intangible Assets | Maximum
Amortizable intangible assets
Useful life of finite-lived intangible assets	10 years
Other Intangible Assets | Weighted Average
Amortizable intangible assets
Useful life of finite-lived intangible assets	7 years
Customer Relationships and Acquisition Costs
Amortizable intangible assets
Gross carrying amount	$ 937,174	904,866
Accumulated amortization	333,860	297,029
Customer Relationships and Acquisition Costs | Amortization Expense Included In Depreciation And Amortization [Member]
Amortizable intangible assets
Amortization of Intangible Assets	43,614	46,733	37,725
Customer Relationships and Acquisition Costs | Amortization Expense Charged To Revenues [Member]
Amortizable intangible assets
Amortization of Intangible Assets	$ 11,670	$ 11,715	$ 11,788