Income Taxes Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2017		Sep. 30, 2017	[1]	Jun. 30, 2017	[1]	Mar. 31, 2017	[1]	Dec. 31, 2016	[1]	Sep. 30, 2016	[1]	Jun. 30, 2016	[1]	Mar. 31, 2016	[1]	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Income Tax Expense Components [Line Items]
Federal	$ 12,900
Total deferred expense/(benefit)																	$ 22,845		$ 2,777		$ (4,575)
Income tax expense	$ 21,391	[1]	$ 8,289		$ 9,963		$ 6,553		$ 7,247		$ 8,652		$ 7,626		$ 7,438		46,196	[2]	30,963	[2]	30,392	[2]
Income Tax Expense Components, Continuing Operations [Member]
Income Tax Expense Components [Line Items]
Federal																	17,176		20,237		25,631
State																	6,509		7,778		9,183
Total current expense																	23,685		28,015		34,814
Federal																	19,820		1,976		(3,185)
State																	2,691		972		(1,237)
Total deferred expense/(benefit)																	22,511		2,948		(4,422)
Income tax expense																	$ 46,196		$ 30,963		$ 30,392

[1] Due to rounding, the sum of the four quarters may not add to the year to date total.

[2] The Company’s effective tax rate for 2017, 2016, and 2015 is not consistent due to the re-measurement of the deferred tax assets, impairment of goodwill not deductible for tax purposes, earnings from tax-exempt investments, non-deductible compensation, state and local taxes, income tax credits and income attributable to noncontrolling interests having a different impact on the effective tax rate due primarily to the different levels of income before taxes in years 2017, 2016, and 2015. See Part II. Item 8. “Financial Statements and Supplementary Data - Note 17: Income Taxes” for additional details.