Basis of Presentation - Adoption of New Accounting Standards (Details) - USD ($) $ in Thousands		Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Right-of-use assets - operating leases		$ 164,659	$ 146,000	$ 0
Lease liabilities - operating leases		$ 205,167	178,000	0
Accounting Standards Update 2017-08
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for adoption of ASU, net of tax	[1]			(583)
Retained Earnings | Accounting Standards Update 2017-08
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cumulative adjustment for adoption of ASU, net of tax			$ (583)	$ (583)	[1]

[1] See "Adoption of New Accounting Standards" in Note 1—“Basis of Presentation” of the “Notes to Interim Consolidated Financial Statements (unaudited)” under Part I, Item 1 of this report for additional details.