Summary of Significant Accounting Policies (New Accounting Pronouncements Adopted) (Details) - USD ($) $ in Thousands		Jan. 01, 2018	Jan. 01, 2019
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Marketable equity securities		$ 31,900
Cumulative effect of change in accounting principle	[1]	(160)
Reclassification of tax effects in AOCI resulting from the new federal corporate income tax rate	[2]	0
Retained Earnings
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Cumulative effect of change in accounting principle	[1]	(545)
Reclassification of tax effects in AOCI resulting from the new federal corporate income tax rate	[2]	6,656
Retained Earnings | Accounting Standards Update 2018-02
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Reclassification of tax effects in AOCI resulting from the new federal corporate income tax rate		6,656
Retained Earnings | Accounting Standards Update 2016-01
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Cumulative effect of change in accounting principle		(545)
AOCI, net of Tax
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Cumulative effect of change in accounting principle	[1]	385
Reclassification of tax effects in AOCI resulting from the new federal corporate income tax rate	[2]	(6,656)
AOCI, net of Tax | Accounting Standards Update 2018-02
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Reclassification of tax effects in AOCI resulting from the new federal corporate income tax rate		(6,656)
AOCI, net of Tax | Accounting Standards Update 2016-01
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Cumulative effect of change in accounting principle		$ 385
Forecast | Accounting Standards Update 2016-02
New Accounting Pronouncements Adopted and Recent Accounting Pronouncements [Line Items]
Cumulative effect of change in accounting principle			$ 14,700
Right-of-use, lease asset			114,600
Right-of-use, lease liability			$ 120,400

[1] Represents the impact of the adoption of Accounting Standards Update (“ASU”) 2016-01, Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities in the first quarter of 2018. Refer to Note 1 — Summary of Significant Accounting Policies to the Consolidated Financial Statements for additional information.

[2] Represents amounts reclassified from AOCI to retained earnings due to the early adoption of ASU 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income in the first quarter of 2018. Refer to Note 1 — Summary of Significant Accounting Policies to the Consolidated Financial Statements for additional information.