Stockholders' Equity - Repurchase Programs (Details) - USD ($)	1 Months Ended	3 Months Ended			9 Months Ended	49 Months Ended
	Feb. 01, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2018	Feb. 01, 2019	Jan. 31, 2019
Class of Stock [Line Items]
Repurchased stock acquired average cost per share (in dollars per share)					$ 115.22
Shares repurchased (in shares)					1,400,699
Dollar value of shares repurchased		$ 26,660,000	$ 124,736,000	$ 9,999,000	$ 161,395,000
Subsequent Event
Class of Stock [Line Items]
Repurchased stock acquired average cost per share (in dollars per share)						$ 87.01
Shares repurchased (in shares)	0					5,123,201
Dollar value of shares repurchased						$ 445,788,000
Dollar value of shares that may yet be repurchased	$ 350,212,000					$ 350,212,000	$ 350,212,000
Subsequent Event | 2019 Stock Repurchase Plan
Class of Stock [Line Items]
Authorized amount of shares to repurchase							$ 261,000,000