Income Taxes Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current expense:
Federal									$ 20,165	$ 17,176	$ 20,237
State									12,152	6,509	7,778
Total current expense									32,317	23,685	28,015
Deferred expense:
Federal									2,857	19,820	1,976
State									2,363	2,691	972
Total deferred expense									5,220	22,511	2,948
Income tax expense	$ 8,651	$ 5,461	$ 17,399	$ 6,026	$ 21,391	$ 8,289	$ 9,963	$ 6,553	$ 37,537	$ 46,196	$ 30,963