Our supplemental consolidated financial information for each three month period in 2018 and 2017 are as follows:



	Three months ended
(Dollars in thousands, except per share amounts)	March 31,			June 30,			September 30,			December 31,
2018:
Interest income	$	432,398		$	481,301		$	513,313		$	542,897
Interest expense	12,535			14,858			20,091			28,437
Net interest income	419,863			466,443			493,222			514,460
Provision for credit losses	27,972			29,080			17,174			13,644
Noninterest income	155,518			192,689			210,070			186,707
Noninterest expense	265,417			305,739			309,445			307,592
Income before income tax expense	281,992			324,313			376,673			379,931
Income tax expense	73,966			77,287			95,308			105,000
Net income before noncontrolling interests	208,026			247,026			281,365			274,931
Net income attributable to noncontrolling interests	(13,065		)	(9,228		)	(6,548		)	(8,667		)
Net income available to common stockholders	$	194,961		$	237,798		$	274,817		$	266,264
Earnings per common share—basic	$	3.69		$	4.48		$	5.16		$	5.01
Earnings per common share—diluted	3.63			4.42			5.10			4.96
2017:
Interest income	$	320,926		$	353,927		$	385,271		$	405,016
Interest expense	10,933			11,231			11,297			11,310
Net interest income	309,993			342,696			373,974			393,706
Provision for credit losses	30,734			15,806			23,522			22,242
Noninterest income	117,659			128,528			158,778			152,266
Noninterest expense	237,633			251,246			257,761			264,015
Income before income tax expense	159,285			204,172			251,469			259,715
Income tax expense	51,405			71,656			97,351			135,051
Net income before noncontrolling interests	107,880			132,516			154,118			124,664
Net income attributable to noncontrolling interests	(6,397		)	(9,323		)	(5,498		)	(7,454		)
Net income available to common stockholders	$	101,483		$	123,193		$	148,620		$	117,210
Earnings per common share—basic	$	1.94		$	2.34		$	2.82		$	2.22
Earnings per common share—diluted	1.91			2.32			2.79			2.19