Stockholders' equity - ASR - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jan. 30, 2020	Mar. 31, 2020		Mar. 31, 2019
Stockholders Equity Note
Common stock purchases		$ 502,801	[1]	$ 253,119	[2]
Accelerated share repurchase early termination (Shares)		642,400
Treasury stock
Stockholders Equity Note
Common stock purchases		$ 425,735	[1]	200,449	[2]
Capital surplus
Stockholders Equity Note
Common stock purchases		$ 77,066	[1]	52,670	[2]
Accelerate Share Repurchase
Stockholders Equity Note
Stock repurchase program authorized amount	$ 500,000			$ 250,000
Accelerated share repurchases price paid per share				$ 53.58
Accelerated share repurchases settlement receipt	$ 500,000			$ 250,000
Common Shares Repurchased Accelerated Share Repurchase Agreements				1,165,607
Initial shares received as part of an accelerated share repurchase program	7,055,919			3,500,000
Accelerated share repurchase early termination (Shares)		642,400
Accelerate Share Repurchase | Treasury stock
Stockholders Equity Note
Common stock purchases	$ 400,000	$ 23,000		$ 200,000
Accelerate Share Repurchase | Capital surplus
Stockholders Equity Note
Common stock purchases	(100,000)	$ 23,000		$ (50,000)
Accelerate Share Repurchase | COVID-19
Stockholders Equity Note
Common shares repurchased agreement to be received	$ 167,000

[1] On January 30, 2020, the Corporation entered into a $500 million accelerated share repurchase transaction with respect to its common stock, which was accounted for as a treasury stock transaction. Refer to Note 18 for additional information.

[2] During the quarter ended March 31, 2019, the Corporation entered into a $250 million accelerated share repurchase transaction with respect to its common stock, which was accounted for as a treasury stock transaction. Refer to Note 18 for additional information.