Operations and Summary of Significant Accounting Policies - Revision of Prior Period Financial Statements, Equity Statement (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning balance retained earnings	$ 1,637,392	$ 1,663,671	$ 1,663,671	$ 1,516,044	$ 1,440,669	$ 1,361,406
Beginning balance - Amount	2,772,596		2,801,321	2,647,071	2,560,718	2,480,308
Ending balance retained earnings	1,600,639	1,637,392	1,663,671	1,663,671	1,516,044	1,440,669
Ending balance - Amount	2,734,755	2,772,596		2,801,321	2,647,071	2,560,718
Previously Reported
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning balance retained earnings	1,668,329		1,694,608	1,537,425	1,461,893	1,381,492
Beginning balance - Amount	2,803,533		2,832,258	2,668,452	2,581,942	2,500,394
Ending balance retained earnings		1,668,329		1,694,608	1,537,425	1,461,893
Ending balance - Amount		2,803,533		2,832,258	2,668,452	2,581,942
Revision of Prior Period, Error Correction, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Beginning balance retained earnings	30,937		(30,937)	(21,381)	(21,224)	(20,086)
Beginning balance - Amount	$ 30,937		$ (30,937)	(21,381)	(21,224)	(20,086)
Ending balance retained earnings		30,937		(30,937)	(21,381)	(21,224)
Ending balance - Amount		$ 30,937		$ (30,937)	$ (21,381)	$ (21,224)